Ordovician chitinozoa from western Newfoundland

Review of Palaeobotany and Palynology, 18(1974): 187--221 :c)Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

ORDOVICIAN CHITINOZOA FROM WESTERN NEWFOUNDLAND

RICHARD S. W. NEVILLE

Department of Geology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada* (Accepted for publication June 7, 1974)

ABSTRACT Neville, R. S. W., 1974. Ordovician Chitinozoa from western Newfoundland. Rev. Palaeobot. Palynol., 18: 187--221. Well-preserved Chitinozoa have been obtained from the uppermost part of the autochthonous sedimentary sequence of the Port au Port Peninsula in western Newfoundland, Canada. The taxa, which are described and illustrated by both optical and scanning electron micrographs, date the sequence as Caradocian. The microfauna resembles Upper Ordovician assemblages previously recorded from the Baltic, Britain, Oklahoma and Sweden. Cyathochitina jenkinsi sp. nov. is described and seven new forms are informally delineated.

INTRODUCTION N e w f o u n d l a n d lies at the n o r t h e a s t e r n end o f the A p p a l a c h i a n M o u n t a i n S y s t e m a n d has been divided s t r u c t u r a l l y into three units (Williams, 1 9 6 4 ) by using t w o m a j o r fault zones ( F i g . l ) . The resulting units are here referred to as the western, central and eastern structural units and t h e y c o r r e s p o n d respectively t o t h e Western P l a t f o r m , Central Mobile Belt a n d A v a l o n Platf o r m o f a u t h o r s (e.g. Neale, 1972). The western a n d central units have been subdivided into t w o and five t e c t o n o s t r a t i g r a p h i c divisions respectively ( F i g . l , Zones A and B and Zones C to G o f H. Williams et al., 1 9 7 2 ; Neale, 1972). The area dealt with in this p a p e r lies o n the n o r t h w e s t coast of the P o r t au P o r t Peninsula ( F i g . 2 ) w h i c h f o r m s part o f Z o n e A in the western structural unit. The C a m b r o - O r d o v i c i a n strata of t h e western structural unit belongs to t w o facies, one essentially c a r b o n a t e , the o t h e r clastic. The latter were originally c o n s i d e r e d (e.g. S c h u c h e r t and D u n b a r , 1 9 3 4 ) to c o n f o r m a b l y overlie the c a r b o n a t e s . T h e s u b s e q u e n t discovery o f fossils p r o v i n g t h a t at least parts o f t h e t w o facies were c o n t e m p o r a n e o u s , however, disproved this hypothesis. *Present address: Robertson Research International Limited, 'Ty'n-y-Coed', Llanrhos, Llandudno, North Wales, Great Britain.

188 r 58o*

[

540W

LEGEND AIIochlhonous c l o s h c rOCkS f o r m i n g the kl,ppen o f t h e w e s t e r n s l r u c t u r o l u n i t

"'7

Major

fuult

P,~s

/

/

.*,~,

/

A "~//~

E

POtT AU P O R T PENINSULA

1/I

..y_

"11J

,l

of tectono-s~ro~=qropmc

subdlv's,on$ ( Z o n e s A-H o f Wlllloms el ol 1972 ~ d Neole 1972) _

.,-; ;i-

GULF OF S?T L A W R E N C E

--],,

zones

--~----

OCEAN

_ &~C,'.~,',, 4'" 4 -

"/'3

i~

5..

G

x"

...." I..

47ON

4?ON--

SCALE kmS 0

I00

57o~

51o,

Fig.1. Sketch map of the Island of Newfoundland showing the three major structural units, the eight tectonostratigraphic subdivisions and the klippen of the western structural unit (mainly after Williams, 1 967, and Neale, 197 2, riga ). A l t h o u g h it had b e e n suggested by o t h e r authors (e.g. J o h n s o n , 1 9 4 1 ) that s o m e o f t h e clastic r o c k s were a l l o c h t h o n o u s , it was R o d g e r s and N e a l e ( 1 9 6 3 ) w h o f o r m a l l y p r o p o s e d t h e n o w w i d e l y a c c e p t e d v i e w that there are in w e s t e r n N e w f o u n d l a n d t w o C a m b r o - O r d o v i c i a n k l i p p e n c o m p o s e d essentially o f clastic rocks. T h e s e a u t h o r s f o l l o w e d earlier m a p s and placed

189

59°10' W

THREE ROCK

a,& GUL r

SK

OF

LAWRENCE

fPORT

AU PORT PENINSULA

]

1

n8o 55' N~

I

SECTIONS SAMPLED

/y

/

~

\

Waterfol~/ /•

\.

SCALE

'I

"/'kms 0

2

3 k~

i/

Fig.2. Map showing the locations of the sections sampled during the present study.

Stevens (1970, p.170) has estimated the thickness of these autochthonous breccias, limestones and shales as approximately 500 ft. (155 m). Port au Port Peninsula t h e y lacked information in placing the limits of the klippe. Because of facies similarities the sequence sampled for this study had first been interpreted as belonging to the southern klippe which is centred on the Bay of Islands (Rodgers and Neale, 1963, fig.l; Riley, 1962). Subsequent more detailed studies (Stevens, 1970; Brtickner, personal communication, 1970) have shown that klippe rocks are preserved only on the northern side of the Port au Port Peninsula (Fig.l) and that the sequence sampled by the author represents the uppermost part of the autochthonous sequence. The coastal section from Cape Cormorant to Mainland (Fig.2) begins with limestone breccias which on the hill above the cape can be seen to unconformably overlie well-bedded limestones which belong to the Table Head Group (Schuchert and Dunbar, 1934). In the basal part of the section the breccia beds are very thick and coarsegrained and contain some very large boulders. Going up the sequence the breccia beds generally become thinner and finer-grained with interbedded shale layers increasing in number and thickness and some limestones occurring. A few thin sandy beds appear in the shales at about the same level as the uppermost breccia layers. This sequence, because of its stratigraphic position and facies, represents the upper parts of the Table Head Group, and

190

the klippen.boundaries at or near the junction between the carbonates and clastics. Th ey admit (loc. cit. p.721) that particularly in the west part of the Towards Mainland more and m or e sandstone beds are intercalated in the shales. F r o m Mainland to a p p r o x i m a t e l y as far as Three Rock Point the coastal belt is also underlain by shale and sandstone. Stevens (1970, p.171) refers to this as a flysch sequence of easterly derivation and has estimated its thickness as being between 3,000 and 4,000 ft. (900--1200 m approximately). A rock o u t c r o p awash in the sea a few hun dred metres west of Mainland is limestone o f the Long Point F o r m a t i o n (Schuchert and Dunbar, 1934), and the same rock t y p e forms Three Rock Point. The nature of the basal contact of the Long Point limestones is not ascertainable within the area dealt with here, as the c o n t a c t lies beneath the sea off Mainland and is not exposed at Three Rock Point. Farther to the northeast, however, the Long Point F o r m a t i o n u n c o n f o r m a b l y overlies klippe rocks. Rodgers (1965, pp.86--87) has thus revived the original hypothesis of Schuchert (Schuchert and Dunbar, 1934, p.72) and considers the basal cont act to be u n c o n f o r m a b l e even farther to the southwest. Stevens (1970, p.171) prefers to assume that, southwest of Three Rock Point, the Long Point F o r m a t i o n overlies the a u t o c h t h o n o u s flysch sequence c o n f o r m a b l y and gradationally. The Table Head G r oup has been informally divided into three members (Schuchert and Dunbar, 1934; Whittington and Kindle, 1963). F~hraeus (1970), from c o n o d o n t studies, considers t ha t the lower and middle " m e m b e r s " of the Table Head Group at the t y p e locality of Table Point (Fig.l) have a Llanvirnian age with the top of the middle " m e m b e r " probably corresponding to a high level in this stage. Stevens (1970, p.170), referring to unpublished work by Ffihraeus, indicates that all " m e m b e r s " of the Table Head G r oup may be diachronous units, each becoming progressively y o u n g e r from east to west. He notes in particular that based on conodonts it is suggested that the middle Table Head at Hare Bay is older than the t y p e middle Table Head. In addition part of the lower Table Head on the Port au Port Peninsula seems to be as y o u n g as the type middle Table Head. Stevens {1970, pp.171 and 173) placed a Llanvirnian--Llandeilian age on the flysch-like sequence of the Mainland area, the youngest graptolites f o u n d in it belonging to zone 10 of Berry {1960). Stevens, following Rodgers (1965), assigned a y o u n g e r Wilderness age to the Long Point Formation. Berry (1960) correlated the Wilderness Stage with his zone 12 and also the lower Caradocian (see also A. Williams et al., 1972, fig.2). According to the c o n o d o n t studies of F~hraeus (1973), however, this form at i on belongs to the middle Caradocian and its base " . . . probably coincides with the base of the Climacograptus peltifer Zone of the British standard graptolite zonation and with th at of the Prionodus gerdae c o n o d o n t s u b z o n e " (see also BergstrSm, 1971; A. Williams et al., 1972). The present paper is an a t t e m p t to date parts of the a u t o c h t h o n o u s sequence of the Mainland area using Chitinozoa.

191 LOCATIONS OF SAMPLES STUDIED Three sections were sampled during the present study (Fig.2). Section 1 corresponds to the transition zone from the Table Head limestone breccias to the shale--sandstone ( " f l y s c h " ) sequence. Sections 2 and 3 are well within the latter and stratigraphically close to one another, with section 3 probably being slightly higher in the sequence than section 2, though still a fair distance below the younges t preserved strata of this unit (Brfickner and Stevens, personal communications, 1972, 1973). In all, 23 samples were collected and the sections given in Appendix I indicate their a p p r o x i m a t e positions and descriptions from hand specimens. TECHNIQUES OF PREPARATION AND STUDY The preparation m e t h o d e m p l o y e d in the present study was based on t hat used by Jenkins (1967, p.440). T w e n t y grams of sediment (100 g in the case of the three limestone samples PPL1, PPL2 and PPL3) were broken into fragments ab o u t 0.5 cm in diameter and the calcareous minerals present removed with dilute h y d r o c h l o r i c acid; 52% hydrofl uori c acid was used to remove the clay minerals and silica and to disaggregate the samples. After neutralising, the samples were sieved in a BS300 mesh sieve (53a). Final c o n cen tr atio n of the Chitinozoa and other coarse fractions of the organic residue was achieved by heavy-liquid separation using a c o n c e n t r a t e d solution of zinc bromide (s.g. 2.2) and centrifuging. At this stage the scolecodonts and graptolite siculae were usually c o u n t e d and removed for mounting. Some however were bleached using the m e t h o d outlined below for the chitinozoans. Due to natural oxidation some of the chitinozoans did not need bleaching. Some of the opaque specimens were left unbleached but most were oxidised in the laboratory. Several oxidising agents were used to try their bleaching effects on the Chitinozoa. Sodium h y p o c h l o r i t e and hydrogen peroxide were tried on several specimens but over a 12-h period neither apparently had any visible effects. A 5% solution of potassium h y d r o x i d e used after an initial partial bleaching using Schulze's solution or potassium chlorate and fuming nitric acid served only to make the chitinozoans curl and subsequently break up. Bleaching o f the Chitinozoa was finally achieved by using fuming nitric acid with in some cases addition of potassium chlorate. Schulze's solution on its own proved to be t oo slow, but with the addition of fuming nitric acid it proved adequate in some instances. The bleachings were carried out in a covered Petri-dish and the reactions observed i n t e r m i t t e n t l y under a lowpower binocular microscope. The bleaching was terminated by transferring the specimens to a Petri-dish containing distilled water. The chitinozoans were now ready to be mounted. Some of them were transferred to a watch-glass by using a pipette and as much of the water as possible was removed. Clearcol solution was then added to the residue in the

192 watch-glass and each individual chitinozoan was transferred to a glass slide using a fine pipette. The drops of Clearcol, each containing a chitinozoan, were aligned in rows on the slides, each slide usually having only one species. Excess Clearcol was removed from each drop and the slides were left under a cover to dry. This procedure was cont i nued until all the chitinozoans in the Petri-dish had been m o u n t e d . The chitinozoans on the glass slides were finally p r o t e c t e d by coverslips using Canada balsam as the cementing medium. All the slides were then numbered, beginning with the sample number, and the p h o t o g r a p h e d specimens ringed. Specimens were p h o t o g r a p h e d on a Zeiss Standard RA Research Microscope using an Asahi Pentax a t t a c h m e n t and Kodak Panatomic X film and a Zeiss P h o t o m i c r o s c o p e with Ilford PAN F film. Apart from study using an optical microscope, some of the Chitinozoa were prepared for study in a scanning electron microscope. The specimens were dried out on aluminium studs and coated with gold in a Balzers vacuum coating unit (Micro--BA3) after the m e t h o d of Barber and Boyde (1968). Specimens were studied on a Cambridge Instrument Com pany " S t e r e o s c a n " scanning electron microscope (SEM) Mh2A operating at a beam accelerating voltage of 5, 10 or rarely 20 LV, micrographs being recorded during single 40- or 100-sec scans. For all the samples studied, the num be r of Chitinozoa, graptolite siculae and scolecodonts recovered from 20 g of rock (100 g for samples PPL1, PPL2 and PPL3) were counted. The results are shown in Table I where it can be seen th at the abundance of Chitinozoa varied from 0.1 per g in sample PP5 to 85.7 per g in sample PP18. These figures are considered to be only approximate since a repeat preparation of 20 g of sample PP15 with subsequent counting gave a Chitinozoa density of only 1.8 per g. This compares with a density of 3.1 Chitinozoa per g obtained from the first preparation. Although for several of the samples more material was studied than was prepared for the quantitative study, no additional forms were encountered. All the slides are in the author's personal collection but u n f o r t u n a t e l y many of the specimens studied on the SEM have been lost. SYSTEMATIC DESCRIPTIONS The Chitinozoa seen during the present study were generally highly flattened. This is in contrast to the relatively uncrushed state of much of the material described by other authors, e.g. Eisenack (1931, 1959, 1968a, etc.) and Jenkins (1967, 1969, 1970a). In many of the bleached specimens it has been possible to observe that the aboral ends have collapsed inwards. The degree of basal invagination can result in a variety of silhouettes from identical forms, but if enough specimens are examined then this factor does not hinder or prevent identification. The classification established by Eisenack based on straightforward m o r p h o l o g y has been adopt ed here. It has been used here in preference to the classification proposed by Jansonius (1964) because it is more widely

193 TABLE I Chitinozoa, graptolite siculae and scolecodont abundances in 20 g preparations (100 g for samples PPL1, PPL2 and PPL3). Samples

Chitinozoa

Graptolite sieulae

PP 10 PP 9 PP 8 PP 7 PP 6 PP 5 PP 4 PP 3 PP 2 PP 1 PP 20 PP 19 PPL3 PPL2 PPL1 PP 18 PP 17 PP 16 PP 15 PP 14 PP 13 PP 12 PPll

255 79 252 4 16 2 53 219 142 94 230 777 50 380 5272 1715 296 43 63 241 257 616 705

25 5 67 1 3 -13 12 12 88 179 26 1? 30 74 14 41 297 253 225 58 i2 54

Scolecodonts 2

Chitinozoa per g of rock 12.7 3.9 12.6 0.2 0.8 0.1 2.6 10.9 7.1 4.7 11.5 38.8 0.5 3.8 52.7 85.7 14.8 2.1 3.1 12.0 12.8 30.8 35.2

7 1 3 -4 3 -3 38 9 9 32 85 23 52 31 68 43 36 15 23

used by Chitinozoa workers and for the reason outlined by Jenkins (1967, p.442). T h e presen t a u t h o r has used the descriptive t e r m i n o l o g y established b y C o m b a z a n d P o u m o t ( 1 9 6 2 ) a n d s u b s e q u e n t l y a d o p t e d b y t h e subcommittee for chitinozoans of the International Committee of the Microflora of the Palaeozoic. T h e d i s t r i b u t i o n a n d f r e q u e n c i e s o f t h e t a x a r e c o r d e d ar e g i v e n in F i g . 3 . G e n u s Ancyrochitina E i s e n a c k , 1 9 5 5 a

Type species: Ancyrochitina ancyrea ( E i s e n a c k , 1 9 3 1 ) E i s e n a c k , 1 9 5 5 a Ancyrochitina ? alaticomis J e n k i n s , 1 9 6 7 ( P l a t e I, 1)* Dimensions in microns (1 s p e c i m e n m e a s u r e d ) " Total length

Chamber length

Maximum diameter

Oral tube length

Oral tube diameter

Apertural diameter

Appendage length

157+

112

70

45+

45

~

22

Remarks. T h e s i n g l e d a m a g e d s p e c i m e n r e c o r d e d m a y in f a c t be a s p e c i m e n o f Ancyrochitina alaticornis J e n k i n s . H o w e v e r , t h e p o o r s t a t e o f p r e s e r v a t i o n *For Plates see pp. 209--215.

194

\

01

~

~ ~ ~ , _ ~

=

~

~ ~- ~ o

~_

~

_~ ~

~ < ~

ECIES

_

~-

~-

V-

~-

<

F--

~-

-

S AMPLE S~ IN

(t)

STRA::;:~PHICAL~

(J

PP 9

~)

,

PP 8

t(..)

PP 7

u~

PP 6 PP

5

oJ

PP 4

z

PP

0 I-,,.) bJ co

m

• '!? , , ,

PP I0

zi 0

_ (J

3

PP 2 PP

I

PP 20 PP

I

ii

19

PPL3 PPL 2

I

PPLI --

P P 18

Z 0

P P 17

I'LIJ u~

I

KEY NO. OF SPECIMENS PER 20g OF ROCK

PPI6

> 30

ABUNDANT

PP 15

16-30

VERY

PP 13

6-15 2-5

COMMON UNCOMMON

PP 12

I or < I

RARE

P P 14

PPII

f

COMMON

l

Fig.3. The qualitative and quantitative distribution of Chitinozoa in the samples studied.

and the simple nature of the only intact appendage only allow for a questionable assignment. Genus Conochitina Eisenack, 1931 restr. 1955b Type species." Conochitina claviformis Eisenack, 1931

Conoehitina chydaea Jenkins, 1967 (Plate I, 2--27)

195

Dimensions in microns (75 specimens measured): Total length

Maximum diameter

Oral tube diameter

Oral tube length

Apertural diameter

Range 115--256 64--95 42--58 37--93 32--63 Mean 173 83 51 60 45 Remarks. Although the range of the total length (115--256p) is less than that recorded by Jenkins (1967, 123--323p), in the original description of the species the mean values for the total length and ot her parameters are very similar. The specimens described here are likewise very variable in shape with shoulders being absent (Plate I, 2), slightly developed (Plate I, 7) or relatively strongly developed (Plate I, 22) resulting in necks which may flare and occupy between 20% and 50% of the total length. Many of the specimens are stouter than those recorded by Jenkins (1967) with the ratio total length/ m a x i m u m diameter being between 1.5:1 and 3.7:1 with a mean value of 2.0:1. These stout forms fall on the fringes of the populations, but since there is continuous variation from such types to typical C. chydaea t h e y are here included within the same species. Whereas the majority of the specimens recorded by Jenkins (1967) was laevigate, the majority r e c or ded here possesses an o r n a m e n t of grana or small cones which rarely exceed 2p in length. Although the o r n a m e n t is largest and often confined to the basal margins, small cones and grana can occur on the flanks. Plate I, 25, 26 show the t w o specimens recovered which show an annular thickening and an annular thinning, respectively. It is not know n definitely what has caused these annular features but it is suggested t hat t h ey are due to growth (cf. Combaz et al., 1967, plate 4, fig. 55; Cramer and Dfez, 1970, plate I, figs. 4 and 9). Plate I, 27 shows a unique specimen in which the prosome is e x p a n d e d aborally into an ovoid shape with a slightly thickened margin. It is included here because of its association with and general similarity to C. chydaea. Conochitina micracantha Eisenack, 1931 (Plate II, 1--13, 15--17) 1969 Conochitina micracantha Eisenack; Jenkins, pp. 10-12, plate I, figs.17--21, textfig.4 (q.v. for further synonymy). ?1971 Conochitina rnicracantha Eisenack; Atkinson and Moy, p. 246, plate 2, fig. N. 1971 Conochitina micracantha Eisenack; Laufeld, p. 293, plate 2, fig. 1. Dimensions in microns (50 specimens measured):

Range Mean

Total length

Maximum diameter

Total length/ Max. diameter

Apertural diameter

147--381 276

67--120 97

2.0:1--4.2:1 2.8:1

41--95 64

Remarks. The n u m e r ous specimens observed are similar to those placed in Conochitina micracantha micracantha forma typica by Eisenack (1965). The writer however follows Jenkins (1969, p.12) who elevated the subspecies C. micracantha micracantha t o specific level.

196 Eisenack's (1965) specimens from the Ostseekalk show similar distribution of ornament to those described here. The ornament, consisting of spines and cones which may reach up to a maximum of 5p in height (Plate II, 7 is the most coarsely ornamented specimen recorded), is coarsest aborally becoming finer orally where it may be absent. Under an optical microscope the processes can only rarely be seen to be complex (e.g. X-shaped). Study under a SEM, however, shows that many, if not most, of the processes in some specimens are in fact complex {Plate II, 12, 13). The specimens described by Jenkins (1969) possess little or no ornament except on the basal margins and adjacent regions. Both Eisenack's and Jenkins' specimens are somewhat more clearly campanulate than those recorded here. Eight campanulate specimens had minimum neck diameters between 2g and 15p less than the corresponding apertural diameter. On these eight specimens the mean values for the neck and apertural diameters were 61p and 67p, respectively.

Conochitina sp. A (Plate II, 14, 18) Dimensions in microns (5 specimens measured):

Range Mean

Total length

Maximum diameter

Apertural diameter

109--134 128

74--86 83

45--51 46

Description. Stout conical test with flat to slightly convex base. Maximum diameter at or near the base, 60--70% of the total length. Aperture between 50--60% of the m a x i m u m diameter. Wall laevigate or bearing small cones. Remarks. In the present study the forms referred to Conochitina chydaea Jenkins have shown a great a m o u n t of variation and the rare forms referred here to Conochitina sp. A may in fact be extreme variants of this species. Genus Cyathochitina Eisenack, 1955b

Type species: Cyathochitina campanulaeformis (Eisenack, 1931) Eisenack, 1955b

Cyathochitina jenkinsi sp. nov. (Plate III, 1--28) Holotype: Plate III, 1, sample PP11. Diagnosis. Test usually divided into chamber and oral tube, the latter being between 25--50% of the total length. Oral tube is cylindrical or slightly tapering, may flare a little and is 45--75% of the maximum diameter in width. Shoulders often only weakly developed and occasionally absent. The maximum diameter is 30--60% of the total length and is situated in the lower half of the test, usually between 0.5--0.75 total length from the oral end. Base usually flat to concave, rarely slightly convex, with the basal margin possessing a translucent carina about 5--10p wide which usually has a slightly

197 thickened margin a b o u t 1--1.5p wide (Plate III, 20, 25). The wall bears fine longitudinal ribbing which is best developed and often restricted t o the aboral end.

Dimensions in microns (50 specimens f r om sample PP11 measured):

Holotype Range Mean

Total length

Chamber length

Maximum diameter

Oral tube length

Oral tube diameter

Apertural diameter

237 205--314 247

154 115--218 157

93 83--125 101

83 58--128 88

54 48--77 61

51 38--70 53

Remarks. Rare specimens possess slightly thickened horizontal bands e.g. Plate III, 23. W. A. M. Jenkins (personal c omm uni cat i on, 1972) considers the specimens described here to be closely similar, if not identical, to a form he r eco r d ed f r o m younger Caradocian rocks of Shropshire, England, in his Ph.D. thesis (1965). In the latter he treated the form as a new species but felt he had n o t enough specimens to publish it formally. The forms described by Eisenack (1962b, table 1) are also probably comparable with C. jenkinsi.

Comparison. Three species can be compared with Cyathochitina jenkinsi sp. nov.: C. calix (Eisenack, 1 9 3 1 ) E i s e n a c k , 1958, C. campanulaeformis (Eisenack, 1931) Eisenack, 1955b, and C. kuckersiana (Eisenack, 1934) Eisenack, 1962a. C. kuckersiana shows stronger differentiation of the oral tube and chamber, and its membranous carina is wider. C. campanulaeformis is stouter and lacks a membranous carina. C. calix is the most similar of the three to C. jenkinsi but its carina is less well-developed and is n o t membranous, and its m a x i m u m diameter is at or close to the aboral end. In addition the stratigraphical ranges of C. calix (Lower Ordovician) and C. jenkinsi (Upper Ordovician) do not overlap. Genus Desmochitina Eisenack, 1931 emend. 1962a Type species: Desmochitina nodosa Eisenack, 1931

Remarks. Much has been written a bout the possible similarities and differences between the three genera Desmochitina, Hoegisphaera Staplin, 1961 and Calpichitina Wilson and Hedlund, 1964. Eisenack (1968b, pp. 155, 185) and Jenkins (1970a, p. 275) consider that Hoegisphaera and its junior s y n o n y m Calpichitina are bot h s ynonym s of Desmochitina. This view is not shared by some authors, including Urban (1972) and Legault (1973a, b). Urban (loc. cit., p.22) em e nde d Hoegisphaera to mention a distal carina. He also considers (p.23) that Calpichitina scabiosa Wilson and Hedlund, 1964 and Hoegisphaera bransoni Wilson and Dolly, 1964 should not be assigned to Hoegisphaera. His main reasons are that the t ype species of the latter genus, H. glabra Staplin, 1961 has a much thicker wall and is more rigid than C. scabiosa or H. bransoni and invariably exhibits an oral-aboral orientation, a preference n o t shown by these other two species. He also suggests that further work on Calpichitina is needed before s y n o n y m y with Desmochitina can be considered.

198 Legault (1973a, b) believes that the genus Hoegisphaera shows a distinct type of aggregation where the individuals are not in direct contact with each other, but are enclosed within a delicate membranous material. He considers this feature important enough to differentiate Hoegisphaera from other Chitinozoa. The genus Hoegisphaera thus appears distinct from Desmochitina and Calpichitina. The latter genus however may prove, with further work, to be a junior s y n o n y m of Desmochitina. It may be pointed out here that Hoegichitina, a proposed replacement for Hoegisphaera Staplin, 1961 by Combaz and Peniguel (1972, p.144) is an "unjustified e m e n d a t i o n " according to Article 33 of the International Code of Zoological Nomenclature (Stoll et al., 1961). It cannot, under the Code, be substituted for Hoegisphaera. Desmochitina cf. lata Schallreuter, 1963 (Plate IV, 1--21) Dimensions in microns (Measurements obtained from several specimens, different compressions providing the various dimensions):

Range Mean

Total length

Maximum diameter

Apertural diameter

51--90 77

64--128 102

32--80 56

Remarks. In the present study numerous specimens have been referable to the genus Desmochitina apart from those assigned to D. minor Eisenack, 1931. The tests occur singly (e.g. Plate IV, 1), in clusters (sensu Jenkins, 1970a, plate 50, fig. 21., e.g. Plate IV, 7) or in chains of up to six individuals (e.g. Plate IV, 9). Bleaching modifies and eventually destroys the sculpture of the b o d y wall and fine sub-concentric ridges and scabrate sculpture can be seen (Plate IV, 13, 20). The difficulty with this group is that, because of their original sub-spherical shape they may be compressed orally/aborally (Plate IV, 13), laterally {Plate IV, 3) or along any intermediate direction (Plate IV, 7). The accompanying stereoscan photomicrographs (Plate IV, 17--19, 21) illustrate these different compressions more clearly. The writer considers that several described species are probably represented here by individuals, among these being Desmochitina bransoni (Wilson and Dolly, 1964) Jenkins, 1969; D. lata Schallreuter, 1963; D. lecaniella Eisenack, 1965; D. monilis Taugourdeau, 1965; and D. scabiosa (Wilson and Hedlund, 1964) Jenkins, 1969. It should be noted that Laufeld (1967, pp.327--328) considers D. scabiosa to be closely related to D. lecaniella and D. bransoni and the latter to be possible synonyms. Also Jenkins (1969, pp.21--22) considers D. monilis to be a junior s y n o n y m of D. lata and the same author (1970a, p.276) regards D. lecaniella as a junior s y n o n y m of D. scabiosa. There thus appears to be a close relationship or even partial s y n o n y m y between all five species. The writer has referred all the specimens described

199 here to D. cf. lata since this is the earliest described species. The specimens recorded here differ from D. lata as figured originally by Schallreuter (1963, plate 2, figs. 11, 12) and subsequently by other authors, e.g. Laufeld (1967, fig. 23) and Jenkins (1970, plate 6, figs. 19--27) by being not so globular and possessing less rounded flanks to the chamber and generally showing somewhat less lateral development of the collar. Some of the specimens may in fact be typical D. lata with the original shape distorted by compression. D e s m o c h i t i n a m i n o r Eisenack, 1931 (Plate V, 1--6, 8--9)

1969 Desmochitina minor Eisenack; Jenkins, pp.20--21, plate 6, figs. 1--18 (q.v. for further synonymy). 1968a Desmochitina minor forma typica Eisenack; Eisenack, p.90, plate 23, figs. 15--16. 1968b Desmochitina minor forma typica Eisenack; Eisenack, p.180, plate 24, figs. 21 and ? 22. ? 1969 Desmochitina minor forma typica Eisenack; Umnova, plate 2, figs. 1--2. 1970 Desmochitina minor Eisenack; Jenkins, pp.275--276, plate 50, figs. 10, 12--17, 19--20. ? 1971 Desmochitina minor Eisenack; Atkinson and Moy, p.246, plate 2, fig. U. 1971 Desmochitina minor Eisenack; Laufeld, p.294, plate 2, fig. P. D i m e n s i o n s in m i c r o n s (10 specimens measured):

Range Mean

Total length

Chamber length

Maximum diameter

Neck diameter

Apertural diameter

83--101 90

72--91 81

64--83 75

34--58 45

34--54 46

R e m a r k s . The few specimens observed all fall within Eisenack's concept of D e s m o c h i t i n a m i n o r forma typica and are comparable in size to those

recorded by Jenkins (1967, 1969) and Laufeld (1967). The sculpture, illustrated here in Plate V, 9 consists essentially of ridges which are often irregular and crested. A single example of two tests joined together was found in sample PP10 (Plate V, 5, 6). D e s m o c h i t i n a sp. A (Plate V, 7) D i m e n s i o n s in m i c r o n s (1 specimen measured):

Total length

Maximum diameter

Apertural diameter

224

166

70

Description. Sub-spherical test with the maximum diameter situated near

the middle. The wall supports a dense ornament of grana. R e m a r k s . D e s m o c h i t i n a sp. A. does not closely resemble any previously

described species. Genus L a g e n o c h i t i n a Eisenack, 1931 T y p e species: L a g e n o c h i t i n a baltica Eisenack, 1931

200

Lagenochitina baltica Eisenack, 1931 (Plate V, 10--16, 18--20; Plate VI, 1--4) Lagenochitina cf. baltica Eisenack, 1931 (Plate V, 17, 21--23) Dimensions in microns (25 specimens measured):

Range Mean

Total length

Chamber length

Oral t u b e length

Maximum diameter

Neck diameter

237--429 320

167--346 240

58--109 81

122--198 152

51--77 63

Remarks. The size range recorded is larger than that recorded by either Jenkins (1967, 196--295p, mean 248~) or Laufeld (1967, 170--352p). The specimens described here also show considerably more variation in shape, from long slender forms (Plate V, 19,20) to short stout forms (Plate V, 10) with the more typical L. baltica (Plate V, 11,12,16,18) being intermediate. The ratio total length/maximum diameter ranges from 1.5:1 to 3.25:1. The usual ornament of L. baltica, consisting of grana or small cones, is illustrated in the SEM photomicrographs (Plate VI, 1--4) although rarely the ornament is so reduced that they are essentially laevigate. The development of shoulders varies greatly in the populations examined and often they are only very weakly developed resulting in poorly defined tapering, rather than cylindrical necks. So great is the morphological variation of forms obviously related to L. baltica that it has been considered necessary to separate off numerous specimens as L. cf. baltica Eisenack, 1931. The latter appear to form part of one very variable population, but are very different from Eisenack's original concept and subsequent authors' interpretations of L. baltica. Forms here included in L. cf. baltica are illustrated in Plate V, 17, 21--23 where it can be seen that there is often a gradual slope with little or no shoulder development from the widest part of the test to the aperture. Strictly such forms even fall outside the circumscription of the genus Lagenochitina, but from their obvious relationships with L. baltica they are here retained within it. The boundary between L. baltica and L. cf. baltica in the present study is of necessity rather arbitrary and somewhat subjective. Lagenochitina sp. A (Plate VI, 5) Dimensions in microns (1 specimen measured): Total length

Maximum diameter

Oral t u b e length

Oral t u b e diameter

461+?

160

128+ ?

70

Description. Large slightly damaged test with cylindrical shaped chamber. Basal margins rounded and base slightly convex. The original shape of the specimen has probably been greatly modified by compression. The wall is laevigate. Remarks. Although basically a very simple form Lagenochitina sp. A does not appear to fall within the circumscription of any species so far described.

201 Lagenochitina sp. B (Plate VI, 6) Dimensions in microns (1 specimen measured): Total length

Chamber length

Maximum diameter

Oral tube length

Oral tube diameter

Apertural diameter

288

±237

147

±51

70

83

Description. Chamber ovoid conical with the maximum diameter slightly nearer the aboral end. The oral tube is poorly differentiated and tapers slightly until just below the aperture it flares strongly. Remarks. Lagenochitina shelvensis Jenkins, 1967 is the most comparable species so far described. It is however, much larger and shows much better differentiation of the oral tube than Lagenochitina sp. B. Genus Rhabdochitina Eisenack, 1931 Type species: Rhabdochitina magna Eisenack, 1931 Rhabdochitina cf. magna Eisenack, 1931 (Plate VI, 7--17) Dimensions in microns (60 specimens measured):

Range Mean

Total length

Maximum diameter

Apertural diameter

320--832 499

70--141 109

54--102 83

The following are dimensions of R. magna given by other authors (in microns): (1) Eisenack, 1931: Total length 500--1000; width 80--100. (2) Eisenack, 1962a : Total length 874--1350, with a mean of 1100; width 80--113, with a mean of 93 (Based on eight complete specimens). (3) Jenkins, 1967: (a) Llanvirnian specimen: Total length 562; maximum diameter 77; apertural diameter 39. (b) Fifteen Llandeilian specimens: Total length 750--909, with a mean of 823; maximum diameter 110--142, with a mean of 131; apertural diameter 90--139, with a mean of 115. Remarks. The specimens observed here vary in shape from almost cylindrical to moderately conical. The basal margins are rounded, the base itself varying from flat to convex. Some of the specimens are probably typical Rhabdochitina magna (Plate VI, 7, 11, 13--15, 17), being similar to Eisenack, 1931, plate 3, figs. 17, 18, and Jenkins, 1967, plate 74, figs. 6, 9--10, 12. No specimens comparable with those illustrated by Eisenack, 1931, plate 3, fig.16 or Eisenack, 1962a, plate 14, fig.1 and plate 15, fig.5 have however been encountered. In view of the latter the relatively few specimens and their comparatively small size they have all been referred to R. cf. magna. It is possible that the majority of specimens described here would lie on the fringes of populations of typical Rhabdochitina magna. Comparison. In the present study there is a gradation from R. cf. magna to

202 Rhabdochitina usitata Jenkins, 1967 but specimens have rarely proved difficult to assign confidently to one or other taxon. Rhabdochitina turgida Jenkins, 1967 (Plate VII, 1--11, 15) Dimensions in microns (30 specimens measured):

Range Mean

Total length

Maximum diameter

Basal diameter

Apertural diameter

189--429 298

99---142 128

77--122 100

48--102 72

Remarks. The size ranges given by Jenkins in the original description of this species (1967) and in a subsequent record of it (1969) are more restricted than that recorded here. There is also more variation in shape from slimmer to stouter forms than recorded by Jenkins (1967, 1969) with the maximum diameter being between 27% and 60% of the total length. The mean values for this relationship are however very similar being 38% by Jenkins (1967) and 42% in the present study. The m a x i m u m diameter is generally positioned lower than in the specimens recorded by Jenkins. It is usually at or between the centre and twofifths total length, but rarely as low as one-quarter total length from the aboral end. Many of the specimens show linear transverse thickenings (Plate VII, 10) comparable with, but on a much smaller scale than those recorded by Laufeld (1967) on Conochitina tigrina. W. A. M. Jenkins (personal communication, 1972) considers the thickenings in the Newfoundland material to be a preservational feature and probably of no taxonomic value. Rhabdochitina usitata Jenkins, 1967 (Plate VII, 12, 13, 16--18) Dimensions in microns (30 specimens measured):

Range Mean

Total length

Maximum diameter

Apertural diameter

237--672 451

74--147 111

54--99 77

Remarks. The above measurements are very similar to those recorded by Jenkins (1967, p.468) in the original description of the species. A few specimens possess a basal process or the basal scar where the process was formerly attached (Plate VII, 17, 18). Measurement of four specimens has given a range of 20--26p with a mean of 23p for the diameter of this basal scar. The specimens range from being slightly slimmer to slightly stouter than those of Jenkins (loc. cit.) with the maximum diameter being between 16--40% of the total length. They are cylindrical to weakly conical in shape with the apertural diameter being between 50--85% of the m a x i m u m diameter. The base is invariably hemispherical.

203 Genus Tanuchitina Jansonius, 1964

Type species: Tanuchitina ontariensis Jansonius, 1964 Tanuchitina bergstroemi Laufeld, 1967 (Plate VII, 14) Dimensions in microns (1 specimen measured): Total length

Maximum diameter

Apertural diameter

Width of basal flange

640

102

77

+10

Remarks. The single specimen has a slightly larger m a x i m u m diameter than those described by Laufeld (1967) from the Upper Caradocian of Sweden. Chitinozoa t y p e A (Plate VII, 19)

Dimensions in microns (1 specimen measured): Total length

Maximum diameter

Apertural diameter

134

70

38

Description. Test ovoid with the m a x i m u m diameter near the middle and a p p r o x i m a t e l y half the total length. Test folded, particularly near the aboral end. The wall supports an o r n a m e n t of cones and hair-like spines up to 3p in height. Remarks. This single specimen does not appear to find suitable inclusion in any described genus.

Chitinozoa ty p e B (Plate VII, 20)

Dimensions in microns (2 specimens measured):

Upper specimen Lower specimen

Total length

Maximum diameter

Apertural diameter

230 224

77 77

9 45

Description. Sub-cylindrical test with a m a x i m u m diameter about one-third of the total length. Near the oral end the test narrows slightly to the aperture. The basal margins are r ounde d and the base convex. The body wall is laevigate. Remarks. The two tests are very closely appressed and the a t t a c h m e n t line between th em is poor l y demarcated. The most suitable genus so far circumscribed for these specimens is Rhabdochitina, but since t hey are unlike any of the species so far described it has been considered better to refer to t hem as a ty p e.

204 Chitinozoa type C (Plate VII, 21)

Dimensions in microns (1 specimen measured): Total length

Maximum diameter

Apertural diameter

397

80

70

Description. Almost cylindrical test which is constricted on both flanks about 65p from the aboral end. It appears to be in part a two layered test with the (?) inner layer (the relationship between the two layers is uncertain) extending about 122p orally from the constriction. Aborally from the latter the test is single layered. The (?) outer layer is ornamented with small cones and spines which are best developed aborally, being very reduced near the oral end. The (?) inner layer which is folded in the region aborally from the constriction possesses only rare small cones. Remarks. This specimen is unlike any other chitinozoan so far described. A possible relationship with Conochitina micracantha Eisenack, 1931 is suggested for three reasons: (1) the ornament of the (?) outer layer; (2) the similar size; and (3) its association with numerous specimens of C. micracantha. THE STRATIGRAPHICAL DISTRIBUTION OF CHITINOZOA IN THE SECTIONS STUDIED In terms of the overall composition of the Chitinozoa assemblages recovered the samples studied can be divided into two groups. The older assemblages (Section 1) from samples P P l l - - P P 2 0 are generally dominated by the three genera Conochitina, Lagenochitina and Rhabdochitina (Fig.3). Conochitina chydaea Jenkins, Lagenochitina baltica Eisenack (+ cf. forms), Rhabdochitina cf. magna Eisenack, R. turgida Jenkins and R. usitata Jenkins are the six commonest chitinozoans throughout the older group. In the younger group (sections 2, 3, samples PP1--PP10) species of Rhabdochitina are much less frequent and Lagenochitina baltica and related forms are also less abundant. Conochitina chydaea dominates most of the assemblages which are fairly rich in Chitinozoa but is joined in this part of the sequence by C. micracantha Eisenack which is often abundant too. Apart from a questionable specimen of C. micracantha in sample P P l l and a single specimen of Desmochitina cf. lata Schallreuter from PPL1, sample PP1 was the oldest record of the former species and of the genus Desmochitina in the present study. D. cf. lata, although only abundant in the youngest sample (PP10), is a fairly consistent constituent of the assemblages in this younger group. In the two youngest samples (PP9 and PP10) it is joined by D. minor Eisenack, although only a few specimens were seen in this study. Cyathochitina jenkinsi sp. nov. is present in both groups but occurs sporadically, being only abundant in the oldest; sample P P l l . The other occurrences of interest are the single specimens of Ancyrochitina ? alaticornis Jenkins and Tanuchitina bergstroemi Laufeld in samples PP17 and PP18 respectively.

205 COMPARISONS WITH ORDOVICIAN CHITINOZOA FAUNAS RECORDED FROM ELSEWHERE Chitinozoa have been described from the Ordovician of North America by Wilson (1958), Wilson and Dolly (1964), Jansonius (1964) Taugourdeau (1965) and Jenkins (1969, 1970a) amongst others. Comparison can best be made with the comprehensive studies of Jenkins (loc. cit.). His 1969 paper deals with the Chitinozoa from the Upper Ordovician Viola and Fernvale Limestones of the Arbuckle Mountains, Oklahoma, and his 1970a paper with those obtained from the unconformably overlying Upper Ordovician Sylvan Shale. Species c o m m o n to the Viola Limestone and the present study are Conochitina micracantha (Jenkins' specimens differed slightly by having little or no ornament on the flanks and neck), Desmochitina minor, Rhabdochitina turgida, R. usitata and probably Desmochitina lata. He also recorded a single specimen which he referred to Lagenochitina cf. baltica but considered that it could have been reworked. Jenkins studied only two samples from the overlying Fernvale Limestone and the only species c o m m o n to both studies is Desmochitina minor. There is less similarity with the assemblages described by Jenkins (1970a) from the slightly younger Sylvan Shale. D. minor is the only species recorded which was also found here, although Desmochitina scabiosa is similar to D. cf. lata and the figured Rhabdochitina sp. (loc. cit. plate 51, fig.14) could fall within the circumscription of R. cf. magna of the present work. Also Jenkins (1970a) on material provided by Dr. Jansonius recorded D. minor and D. scabiosa (related to D. lata) from subsurface Upper Ordovician rocks of Anticosti Island, geographically the closest locality to the present study from which Chitinozoa have been reported. Jansonius (1964) also recorded Hercochitina crichmayi from Anticosti Island and from the subsurface Upper Ordovician Cincinnatian (younger Caradocian--Ashgillian) of Ontario he recovered Cyathochitina (as Tanuchitina) ontariensis and Kalochitina multispinata. None of the last three species has been found in this study. Much of the work in Europe has been done by Eisenack and in numerous publications (e.g. 1958, 1962a,b, 1965) he has discussed the ranges of Chitinozoa in the Ordovician rocks of the Baltic area. He recorded (1962b) Conochitina micracan tha from C 1--F 1 (Upper Llanvirnian--Ashgillian) but Lagenochitina baltica was only found in FI (Ashgillian), although in a later paper (1965) it was recorded from the Caradocian Ostseekalk too. Desmochitina minor forma typica and Rhabdochitina magna and related forms were recorded from B2--F1 (Arenigian--Ashgillian) although R. magna and R. cf. magna were more sporadic in their occurrences. He also recorded Cyathochitina calix from the B:--Ci (Arenigian--Llandeilian) and C. cf. calix from the younger Caradocian (D2--E). The latter forms are probably very similar to C. jenkinsi sp. nov. Laufeld (1967) described the chitinozoans from two Caradocian sections in Sweden. The assemblages have little in c o m m o n with those f o u n d here although he did record Desmochitina minor and Tanuchitina bergstroemi.

206

He also recovered Desmochitina lata and D. lecaniella, both forms which are comparable to the specimens of D. cf. lata recorded here. In a comprehensive study Jenkins (1967) described Chitinozoa assemblages from the Llanvirnian, Llandeilian and Caradocian rocks of Shropshire, England. He recorded several species which have been found in the present study t o o (Table II). Notable forms, recorded by Jenkins (loc. cit.) but not found here, include the genus Siphonochitina from the Llanvirnian and lowest Caradocian, Cyathochitina kuckersiana and the genera Acanthochitina, Ancyrochitina (one poor specimen recorded here) and Angochitina from the Caradocian. Atkinson and Moy (1971) described Lower Caradocian Chitinozoa from North Wales. Of the 23 species they recorded, 4 are the same or similar to forms recovered during the present work; these being Conochitina chydaea, C. micracantha, Desmochitina minor and Rhabdochitina magna. Rauscher (1971) described chitinozoans from Llanvirnian, Llandeilian and Caradocian rocks of Normandy, France. They included Conochitina chydaea (as Euconochitina) from the younger Llanvirnian--Caradocian, C. micracantha (as Pistillachitina) from younger Llanvirnian--older Llandeilian and Desmochitina lata from the younger Llandeilian. His new species Desmochitina (?) mayensis from the younger Llandeilian and Caradocian would appear to include forms here assigned to D. cf. lata. Little Chitinozoa work has been published by workers in Russia. Recently however Umnova (1969) has described the distribution of chitinozoans in the Lower and older Middle Ordovician of the Russian Platform. Conochitina micracantha typica (coarser ornament than the specimens recorded here) was restricted to the Middle Ordovician part of the sequences whilst Desmochitina minor typica was in addition recovered from the younger Lower Ordovician. Rhabdochitina magna was recorded throughout the sequences studied. Taugourdeau and De J e k h o w s k y (1960) and Benoit and Taugourdeau (1961) have described Ordovician faunas from North Africa. In the former publication Cyathochitina cf. calix (possibly comparable with the more elongate slender variants of C. jenkinsi), Lagenochitina cf. baltica and Rhabdochitina magna were recorded. Benoit and Taugourdeau (lot. cit.) also described C. cf. calix (sensu Taugourdeau and De Jekhowsky, 1960) and TABLE II Chitinozoa species present in both the Ordovician of Shropshire, England (Jenkins, 1967) and the Ordovician of western Newfoundland Species

Llanvirnian

Llandeilian

Caradocian

present paper

Conochitina chydaea Desmochitina minor f. typica Desmochitina minor s,1. Lagenochitina baltica Rhabdochitina magna Rhabdochitina turgida Rhabdochitina usitata

X

X

X X X X

X X X X cf. X X

X X X X

X X X

X

207

R. rnagna. In a d d i t i o n t h e y f o u n d C. aff. calix ( p r o b a b l y closer to C. jenkinsi t h a n C. cf. calix), L. baltica a n d R. cf. magna (figured as p l a t e 5, fig.51, is possibly closely r e l a t e d t o Tanuchitina bergstroerai). A r e c e n t p a p e r b y C o m b a z and Peniguel ( 1 9 7 2 ) has d e s c r i b e d C h i t i n o z o a f r o m t h e A r e n i g i a n - - L l a n d e i l i a n r o c k s o f n o r t h - w e s t Australia. T h e y r e c o r d e d Conochitina micracantha micracantha (as Euconochitina) f r o m t h e Llandeilian a l t h o u g h t h e figured s p e c i m e n , p l a t e 3, fig.2 is a d i f f e r e n t s h a p e t o t h o s e d e s c r i b e d here. T h e i r n e w subspecies Euconochitina micracantha tenera f r o m t h e y o u n g e r Llandeilian a p p e a r s v e r y similar t o p a r t o f t h e Conochitina chydaea plexus. T h e n e w species Conochitina p o u m o t i f r o m t h e y o u n g e r Arenigian a n d Llanvirnian w o u l d a p p e a r t o include f o r m s h e r e assigned t o Rhabdochitina cf. magna a n d t h e i r Hoegichitina sp., is similar t o , if n o t identical with, s o m e o f t h e f o r m s h e r e i n c l u d e d in Desmochitina cf. lata.

EXPLANATION OF PLATES PLATE I (Magnification X 220; p.209)

1. Ancyrochitina ? alaticornis Jenkins, PP17K. 2--27. Conochitina chydaea Jenkins; 2, PP9A8; 3, PP9A21; 4, PP9A23; 5, PP9A17; 6, PP9A21; 7, PP9A6; 8, PP9A23; 9, PP9A22; 10, PP9A23; 11, PP9A23; 12, PP9A7; 13, PP9A21 ; 14, PP9A1; 15, PP10A3; 16, PP9A17; 17, PP9A23; 18, PP10G; 19, PP9A1; 20, PP9A22; 21, PP9A1; 22, PP3F; 23, PP8G; 24, PP9A21 ; 25, PP9A1, specimen showing annular thickening; 26, PP9A17, specimen showing annular thinning; 27, PP9A23, specimen showing expanded prosome. PLATE II (Magnification x 220 except where stated; p.210) 1--13, 15--17. Conochitina micracantha Eisenack; 1, PP9A21; 2, PP2A1; 3, PP9A22; 4, PP2A1; 5, PP2A1; 6, PP2A1; 7, PP10K; 8, PP2A1; 9, PP2A1; 10, PP3K. 11--13 and 15--17, SEM micrographs; 11, PP10, part of aboral end, x 500; 12, as 11, detail of sculpture, x 2,500; 13, PP10, detail of sculpture, x 2,500; 15, PP10, X 240;16, as 15, showing invagination of the aboral end, x 490; 17, as 15, details of sculpture of the aboral end, x 2,450. 14, 18. Conochitina sp. A; 14, PP9A7; 18, PP9A22. PLATE III (Magnification X 150 except where stated; p. 211 ) 1--28. Cyathochitina jenkinsi sp. nov.; 1, PP11Q, holotype; 2, PP11Q; 3, PP11M; 4, PPllQ; 5, PPllQ; 6, PPllL; 7, PPllQ; 8, PP11Q; 9, PPllM; 10, PP11M; 11, PPllQ; 12, PPllP; 13, PPllN; 14, PPllP; 15, PPllL; 16, PP11M; 17, PPllP; 18, PPID; 19, PPllP; 20, as 19, part of carina showing thickened margin (x 500); 21, PP11N; 22, PP11N; 23, as 22, shoulder region showing transverse thickenings (x 500); 24, PP11Q; 25, as 24, part of carina showing thickened margin (x 500); 26, PPllL; 27, PPllM. 28, PP11, SEM micrograph illustrating the longitudinal ribs (x 400).

208 PLATE IV (Magnification x 220 except where stated; p. 212) 1--21. Desmochitina cf. lata Schallreuter; 1, PP10W; 2, PP10A1; 3, PPIOA1; 4, PPIOW; 5, PPIOW; 6, PP1OA1; 7, PP4D; 8, PP4B; 9, PP4A; 10, PPIOA1; 11, PP1G; 12, PP1OA1; 13, PP9H, oral view (× 320); 14, as 13, showing membranous flange of the aperture (× 500); 15, PP4C; 16~ PP1A. 17--21, SEM micrographs; 17, PP10, crumpled chain of two specimens (X 130); 18, PP10, lateral view (× 215); 19, PP10, near lateral view of orally/aborally compressed specimen (× 212); 20, as 19, view of oral region (× 425); 21, PP10, chain of two specimens obliquely compressed (x 210). PLATE V (Magnification x 150 except where stated; p.213) 1--6, 8--9. Desmochitina minor Eisenack; 1, PP1OW (× 220); 2, PPIOA1 (× 220); 3, P P I O W ( × 220); 4, P P I O W ( × 220); 5, P P I O W ( × 220); 6, as 5, detail of the attachment region between the two tests (x 440). 8--9, SEM micrographs; 8, PP10, oblique view (X 295); 9, as 8, showing details of sculpture(× 950). 7. Desmochitina sp. A, PP20B. 10--16, 18--20. Lagenochitina baltica Eisenack; 10, PP2OD; 11, PP17L; 12, PP12A17; 13, PP2OC; 14, PP12A17; 15, PP19A; 16, PP2OB; 18, PP2OC; 19, PP2OA; 20, PP2OD. 17, 21--23. Lagenochitina cf. baltica Eisenack; 17, PP12A17; 21, PP19A; 22, PP2OA; 23, PP19D. PLATE VI (Magnification × 100 except where stated; p.214) 1--4. Lagenochitina baltica Eisenack, SEM micrographs; 1, PP14 (x 140); 2, as 1, details of sculpture ( x 4 5 0 ) ; 3 , a s l , details of sculpture ( x 2.350);4, a s l , d e t a i l s o f sculpture (x 4.600). 5. Lagenochitina sp. A, PP9A24 (x 150). 6. Lagenochitina sp. B, PP8H (x 150). 7--17. Rhabdochitina cf. magna Eisenack; 7, PPLIE; 8, PPLIE; 9, PP12A13; 10, PPIOA3: 11, PP14E; 12, PPIOX; 13, PP12A13; 14, PP11X5; 15, PPIOA4; 16, PP14E; 17, PP14M. PLATE VII (Magnification X 150 except where stated; p.215) 1--11, 15. Rhabdochitina turgida Jenkins; 1, PP18A9; 2, PP12A18; 3, PP18A9; 4, PP12A18; 5, PP18A9; 6, P P l l E ; 7, PP8D; 8, PP17I; 9, PP9A2; 10, PP15A, showing irregular transverse thickenings; 11, PP12A18 ; 15, PP18A9. 12--13, 16--18. R h a b d o c h i t i n a u s i t a t a J e n k i n s ; 1 2 , PP10X(x 100); 13, P P 1 2 A 8 ( x 100); 16, PP9A11(× 100);17, PP12X2, showing basal attachment scar (X 100); 18, PP12A8, showing basal attachment scar (x 100). 14. Tanuchitina bergstroemi Laufeld, PP18A9 (× 100). 19. Chitinozoa type A, PP1OW (X 220). 20. Chitinozoa type B, PPSB. 21. Chitinozoa type C, P P 2 A 9 ( × 220).

~J

"0 3~

'0

',,.I

~)

D

T ¸

3~

J 1

0"~

#i ¸

L

i~

ii~i~

=~

b

i~

_

ii

~i ~i!!!i~i~i!ii! ~ ii~

i

¸¸~

~

~ii

iiii

¸

C~

~i ~....

[ i~

........

~ii~i

~ii~i i~

~

iii

~

~~

i

~i........ ii~i~i~i~i~i~i~i~%~i ~

~

¸¸ i

~ii~ii~i~iii~iiii~iiiiiiiiiiiiiiiiiiiilli!iii ~!iiiiii~i i~ii~ii~iiiii ~i~ii~iiiiiii~i

i i

i~i

~

~i~i~i~i~i~iiiiiii~il ~ !~iiiii~iiiiiii~ii~i~iiii i~!i~i~i~!il ~i~iii~i!~!~~i~i~i~i~iill~i~i~iiiiii~il

~

0

•"xl

Pv

"o

~o

.0

-3

b~

D

i.

]

>

-3

I

~a

"-a

F,

5

i J1

]

~

.,4

ii!~i~II~I~i~ii~i~<~i~ ~ii i~i~ii!ili~i~ii~iii~ ~iii~i~i~ iiI

.......i iiii~i !!ii~iiii~!ii~i!iT iii!!i¸¸¸ i ¸¸ T ¸¸ !i~i ¸¸¸¸¸¸¸¸

,J

L m

<

-3

-"

b

J

.,,I

J

m

!

u

o

]

11

~

J~

-]

]

q

-M

216 CONCLUSIONS Four species of chitinozoans, Conochitina micracantha, Cyathochitina jenkinsi, Desmochitina cf. lata and Lagenochitina baltica collectively afford strong evidence that the uppermost part of the autochthonous sedimentary sequence of the Port au Port Peninsula is of Caradocian age: (1) Conochitina micracantha. In Oklahoma (Jenkins, 1969) C. micracantha is confined to the upper part of the Viola Limestone (Caradocian) and in the Baltic (Eisenack, 1962b) it is known from rocks of upper Llanvirnian-Ashgillian age. (2) Cyathochitina jenkinsi. In Britain this species is restricted to the younger Caradocian (Jenkins, 1965). If, as seems likely, it is the same as C. cf. calix (recorded by Eisenack, 1962b, from younger Caradocian rocks of the Baltic) then this species provides firm evidence for a Caradocian age. (3) Desmochitina cf. lata. Outside Newfoundland the Ordovician records of this form and closely similar species recorded under different names appear to be confined to the Caradocian (e.g., Eisenack, 1962a, Kegel Beds of Estonia; Schallreuter, 1963, erratics from the Baltic; Wilson and Dolly, 1964, Tulip Creek Formation of Oklahoma; Eisenack, 1965, the Ostseekalk of north Germany, Gotland and south Finland; Taugourdeau, 1965, and Jenkins, 1969, Viola Limestone of Oklahoma; and Laufeld, 1967, central Sweden) and Ashgillian (Wilson and Hedlund, 1964, and Jenkins, 1970, Sylvan Shale of Oklahoma; and Taugourdeau, 1965, Maquoketa Formation of Iowa). (4) Lagenochitina baltica. The presence of this species is strong evidence for dating the rocks Caradocian or Ashgillian. In northern Europe (Eisenack, 1962b, 1965) L. baltica is restricted to this interval and Laufeld (1967) only recorded it from younger Caradocian rocks in central Sweden. Jenkins (1967) in his Chitinozoa study of sections covering the Caradocian-Llanvirnian from Shropshire, England found L. baltica confined to the Caradocian. The vertical ranges for these four species indicate that the age of the deposits in question is most probably Caradocian. This conclusion is supported by the occurrence of single specimens of Ancyrochitina ? alaticornis and Tanuchitina bergstroemi, both of which are known only from the Caradocian (Jenkins, 1967; Laufeld, 1967). The remaining species encountered in the present study ( Conochitina chyclaea, Desmochitina minor, Rhabdochitina cf. magna, R. turgida and R. usitata) are entirely consistent with a Caradocian age for the rocks concerned, although each is known to occur in older deposits elsewhere. ACKNOWLEDGEMENTS The field and the majority of the laboratory work for this study were carried out while the author held a post-doctoral fellowship in the Department of Geology of Memorial University of Newfoundland, St. John's, Newfoundland.

217

The author would like to thank Dr. E. R. W. Neale, Head of the Geology Department, for allotting ample laboratory and office space to him, and he is very grateful to Dr. W. D. Briickner, J. P. H o w l e y Professor, for having financed this work from his National Research Council of Canada operating grant. The author is especially indebted to Dr. W. A. M. Jenkins, of the Geological Survey of Canada, Dartmouth, Nova Scotia, for his considerable advice and criticisms during the course of this study, as well as for critically reading the draft manuscript. He would also like to thank Dr. Brfickner for assistance in questions of regional geology, for editorial help with parts of the manuscript, and for bringing the introduction of the paper up to date. Thanks are also due to Dr. V. C. Barber of the Biology Department of Memorial University, for operating the SEM and Mr. R. Ficken for developing and printing the resulting micrographs. The grant for the Cambridge Instrument Company "Stereoscan" SEM {NRC (Canada) Major Equipment Grant No. E-2164 } which was made to Dr. A. K. Bal is acknowledged too. The assistance of the Geology Department photographer, Mr. W. Marsh, with photographic work has also been much appreciated. The author is also grateful to Dr. R. H. Cummings for allowing him to use the typing, draughting, photographic and other research facilities of Robertson Research Laboratories in North Wales, where the laboratory work, text and illustrations of this paper were completed. Finally he would like to thank his wife, Sarah, for her considerable assistance throughout the course of this work. APPENDIX 1 Section 1

1 : 5 0 , 0 0 0 T o p o g r a p h i c m a p sheet M a i n l a n d , 1 2 B / 1 1 East Half, 3 7 7 7 9 6 . T h i r t e e n samples were c o l l e c t e d f r o m a p p r o x i m a t e l y 100 m o f coast s e c t i o n n o r t h e a s t o f a waterfall. Near t h e l a t t e r t h e dip o f t h e s t r a t a is 82 ° NNE b u t it decreases g o i n g n o r t h eastwards a l o n g t h e coast. Stratigraphic units Rock types

Samples Thickness (m)

Numbers

Megaseopic d e s c r i p t i o n s

PP 20

dark grey slightly calcareous clayey s i l t s t o n e dark grey calcareous clayey s i l t s t o n e

Top of section limestone shales, siltstones a n d m u d s t o n e s w i t h t h i n layers o f limestone and limestone breccia

1.05

31.00

l i m e s t o n e breccia

0.45

shale

1.10

PP19 ( b o t h samples f r o m near base) PP L3 (from middle part) -

-

light t o dark grey calcirudite with f r a g m e n t s up to 40 m m in d i a m e t e r -

-

218

Samples

Stratigraphic units Rock types

Thickness Numbers (m)

Megascopic d e s c r i p t i o n s

limestone

0.15

light t o dark calcarenite with f r a g m e n t s up to diameter light t o dark calcarenite

PP L2 ( f r o m u p p e r 0.01 m)

PP L1 ( f r o m l o w e r 0.05 m) shales, siltstones a n d m u d s t o n e s w i t h t h i n layers of l i m e s t o n e a n d l i m e s t o n e breccia

PP 18 11.80"

grey a few 10 m m in grey

light t o dark grey calcareous m u d s t o n e ditto dark grey calcareous mudstone ditto ditto dark grey calcareous clayey siltstone ditto light to dark grey calcareous m u d s t o n e

PP 17 PP 16 PP 15 PP 14 PP 13 PP 12 PP 11

l i m e s t o n e breccia ( n e a r 0.60 waterfall) Base o f s e c t i o n Section 2 1 : 5 0 , 0 0 0 T o p o g r a p h i c m a p s h e e t M a i n l a n d , 1 2 B / 1 1 East Half, 4 4 3 8 5 8 . Five samples were c o l l e c t e d f r o m a 3 m t h i c k s e c t i o n o f shales a n d siltstones, d i p p i n g at 10 ° ENE, e x p o s e d in t h e left b a n k of t h e s t r e a m just east o f t h e road.

Sample numbers

Megascopic sample descriptions Top

PP PP PP PP PP

5 4 3 2 1

grey m i c a c e o u s , calcareous s i l t s t o n e ditto ditto grey-green calcareous, clayey siltstone grey m i c a c e o u s , calcareous siltstone Base

Section 3 1 : 5 0 , 0 0 0 T o p o g r a p h i c m a p sheet M a i n l a n d , 1 2 B / 1 1 East Half, 4 3 3 8 5 3 . Five samples were c o l l e c t e d f r o m a 3 m t h i c k s e c t i o n of shales w i t h siltstones, d i p p i n g at 10 ° NNE, e x p o s e d a b o u t 50 m west of t h e road.

Sample numbers

Megascopic s a m p l e descriptions Top

PP 10 PP PP PP PP

9 8 7 6

grey-green slightly calcareous, clayey siltstone dark grey-green slightly calcareous shale grey calcareous, a r e n a c e o u s s i l t s t o n e grey micaceous, calcareous s i l t s t o n e ditto

Base * S a m p l e s f r o m this u n i t t a k e n every 1.5 m a p p r o x i m a t e l y .

219 REFERENCES

Atkinson, K. and Moy, L. R., 1971. Lower Caradocian (Upper Ordovician) Chitinozoa from North Wales. Rev. Palaeobot. Palynol., 11(3--4): 239--250. Barber, V. C. and Boyde, A., 1968. Scanning electron microscopal studies of cilia. Z. Zellforsch. Mikrosk. Anat., 84: 269--284. Benoit, A. and Taugourdeau, P., 1961. Sur quelques chitinozoaires de l'Ordovicien du Sahara. Rev. Inst. Fr. P6t. Ann. Combust. Liquides, 16(12): 1403--1422. Bergstr6m, S. M., 1971. Correlation of the North Atlantic Middle and Upper Ordovician conodont zonation with the graptolite succession. M6m. Bur. Rech. G~ol. Min., 73: 177--187. Berry, W. B. N., 1960. Graptolite faunas of the Marathon region, West Texas. University of Texas Publication, 6005, 179 pp. Combaz, A. and Peniguel, G., 1972. Etude palynoplanctologique de l'Ordovicien dans quelques sondages du Bassin de Canning (Australie occidentale). Bull. Centre Rech. Pau--SNPA, 6(1): 121--167. Combaz, A. and Poumot, C., 1962. Observations sur la structure des Chitinozoaires. Rev. Micropal~ontol., 5: 147--160. Combaz, A., Calandra, F., Jansonius, J., Millepied, P., Poumot, D. and Van Oyen, F. H., 1967. Microfossiles organiques du Pal6ozoique. Les chitinozoaires (2) Morphographie. Published for the Commission Internationale de Microflore du Pal6ozoique by the (:'.entre National de la Recherche Scientifique, Paris, 43 pp. Cramer, F. H. and Dfez, M. D. C. R., 1970. Rejuvenation of Silurian chitinozoans from Florida. Rev. Esp. Micropaleontol., 2(1 ): 45--54. Eisenack, A., 1931. Neue Mikrofossilien des baltischen Silurs, 1. PalSontol. Z., 13: 74--118. Eisenack, A., 1955a. Chitinozoen, Hystrichosph~iren und andere Mikrofossilien aus dem Beyrichia-Kalk. Senckenbergiana Lethaea, 36(1/2 ): 157--188. Eisenack, A., 1955b. Neue Chitinozoen aus dem Silur des Baltikums und dem Devon der Eifel. Senckenbergiana Lethaea, 36( 5/6 ): 311--319. Eisenack, A., 1958. Mikrofossilien aus dem Ordovizium des Daltikums, 1. Markasitschicht, Dictyonema--Schiefer, Glaukonitsand, Glaukonitkalk. Senckenbergiana Lethaea, 39(5/6): 389--405. Eisenack, A., 1959. Neotypen baltischer Silur-Chitinozoen und neue Arten. Neues Jahrb. Geol. Pal/iontol., Abh. 108(1 ): 1--20. Eisenack, A., 1962a. Neotypen baltischer Silur-Chitinozoen und neue Arten (Fortsetzung). Neues Jahrb. Geol. Paliiontol., Abh., 114(3): 291--316. Eisenack, A., 1962b. Mikrofossilien aus dem Ordovizium des Baltikums, 2. Vaginatenkalk bis Lyckholmer Stufe. Senckenbergiana Lethaea, 43(5): 349--366. Eisenack, A., 1965. Die Mikrofauna der Ostseekalke, 1. Chitinozoen, Hystrichosphiiren. Neues Jahrb. Geol. Pal/iontol., Abh., 123(2): 115--148. Eisenack, A., 1968a. Mikrofossilien eines Geschiebes der Borkholmer Stufe, baltisches Ordovizium, F 2 . Mitt. Mineral.-Geol. Inst. Hamburg, 37 : 81--94. Eisenack, A., 1968b. Uber Chitinozoen des baltischen Gebietes. Palaeontographica A, 131: 137--198. F~hraeus, L. E., 1970. Conodont-based correlations of Lower and Middle Ordovician strata in western Newfoundland. Geol. Soc. Am. Bull., 80(7 ): 2061--2076. F~tbraeus, L. E., 1973. Depositional environments and conodont-based correlation of the Long Point Formation (Middle Ordovician), western Newfoundland. Can. J. Earth Sci., 10(12): 1822--1833. Jansonius, J., 1964. Morphology and systematic classification of some Chitinozoa. Bull. Can. Petrol. Geol., 12(4): 901--918. Jenkins, W. A. M., 1965. Ordovician Chitinozoa from Shropshire. Unpublished Thesis, University of Sheffield, Sheffield, 256 pp.

220 Jenkins, W. A. M., 1967. Ordovieian Chitinozoa from Shropshire. Palaeontology, 10(3): 436--488. Jenkins, W. A. M., 1969. Chitinozoa from the Ordovician Viola and Fernvale Limestones of the Arbuckle Mountains, Oklahoma. Spec. Pap. Palaeontol., 5 : 4 4 pp. Jenkins, W. A. M., 1970a. Chitinozoa from the Ordovician Sylvan Shale of the Arbuckle Mountains, Oklahoma. Palaeontology, 13(2): 261--288. Jenkins, W. A. M., 1970b. Chitinozoa. Geoscience Man 1:1--21. Johnson, H., 1941. Paleozoic lowlands of western Newfoundland. N. Y. Acad. Sci. Trans., ser 2(3): 141--145. Laufeld, S., 1967. Caradocian Chitinozoa from Dalarna, Sweden. Geol. FSren. Stockh. F6rh., 89: 275--349. Laufeld, S., 1971. Chitinozoa and correlation of the Molodova and Restevo Beds of Podolia, U.S.S.R. M6m. Bur. Rech. G6ol. Min., 73: 291--300. Legault, J. A., 1973a. Mode of aggregation of Hoegisphaera (Chitinozoa). Can. J. Earth Sci., 10(5): 793--797. Legault, J. A., 1973b. Chitinozoa and Acritarcha of the Hamilton Formation of southwestern Ontario. Geol. Surv. Can., Bull., 2 2 1 : 1 0 3 pp. Neale, E. R. W., 1972. A cross section through the Appalachian orogen in Newfoundland. Int. Geol. Congr., 24th., Montreal, 1972, Field Excursion A62--C62, 84 pp. Rauscher, R., 197].. Les Chitinozoaires de l'Ordovicien du synclinal de May-sur-Orne (Calvados). Soc. Linn. Normandie, Bull., 101(1970): 117--127. Riley, G. C., 1962. Stephenville map-area, Newfoundland. Geol. Surv. Can. Mem., 323, 72 pp. Rodgers, J., 1965. Long Point and Clam Bank Formations, western Newfoundland. Proc. Geol. Assoc. Can., 1 6 : 8 3 --94. Rodgers, J. and Neale, E. R. W., 1963. Possible " T a c o n i c " klippen in western Newfoundland. Am. J. Sci., 261: 713--730. Schallreuter, R., 1963. Neue Chitinozoen aus ordovizischen Geschieben und Bemerkungen zur Gattung Illichitina. Pal//ontol. Abhandl., Geol. Ges. D.D.R., 1(4 ): 391--405. Schuchert, C. and Dunbar, C. O., 1934. Stratigraphy of western Newfoundland. Geol. Soc. Am., Mere. 1 , 1 2 3 pp. Staplin, F. L., 1961. Reef-controlled distribution of Devonian microplankton in Alberta. Palaeontology, 4(3): 392--424. Stevens, R. K., 1970. Cambro-Ordovician flysch sedimentation and tectonics in west Newfoundland and their possible bearing on a proto-Atlantic Ocean. Geol. Assoc. Can., Spec. Pap., 7: 165--177. Stoll, N. R., Dollfus, R. P., Forest, J., Riley, N. D., Sabrosky, C. W., Wright, C. W. and Melville, R. V. (Editors), 1961. International Code of Zoological Nomenclature adopted by the XV Int. Congr. of Zoology, publ. by The Int. Trust for Zool. Nomenclature, London, 176 pp. Taugourdeau, P., 1961. Chitinozoares du Silurien d'Aquitaine. Rev. Micropal6ontol., 4(3): 135--154. Taugourdeau, P., 1965. Chitinozoaires de l'Ordovicien des U.S.A. Comparaisons avec les faunes de l'ancien monde. Rev. Inst. Ft. P6t. Ann. Combust. Liquides, 20(3): 463--485. Taugourdeau, P., 1965. Chitinozoaires de l'Ordovicien des U.S.A. Comparaisons avec les zoaires siluro--d~voniens de quelques sondages de la C.R.E.P.S., de la C.F.P.A. et de la S.N. Repal au Sahara. Rev. Inst. Fr. P~t. Ann. Combust. Liquides, 15(9): 1199--1260. Umnova, N. I., 1969. Rasprostraneniye Chitinozoa v ordovike Russkoy platformy. Paleontol. Zh., 3 : 4 5 - - 6 2 (in Russian; English translation: Distribution of Chitinozoa in the Ordovician of the Russian Platform. In: Paleontol. J., 1969, 3: 326--340). Urban, J. B., 1972. A reexamination of Chitinozoa from the Cedar Valley Formation of Iowa with observations on their morphology and distribution. Bull. Am. Paleontol., 63(275): 43 pp. Whittington, H. B. and Kindle, C. H., 1963. Middle Ordovician Table Head Formation, western Newfoundland. Geol. Soc. Am. Bull., 74: 745--758.

221 Williams, A., Strachan, I., Bassett, D. A., Dean, W. T., Ingham, J. K., Wright, A. D. and Whittington, H. B., 1972. A correlation of Ordovician rocks in the British Isles. Geol. Soc. Lond., Spec. Pap. 3, 74 pp. Williams, H., 1964. The Appalachians in north-eastern Newfoundland - - a two-sided symmetrical system. Am. J. Sci. 262: 1137--1159. Williams, H., 1967. Geology, Island of Newfoundland. Geol. Surv. Can. Map 1231A. Williams, H., Kennedy, M. J. and Nealc, E. R. W., 1972. The Appalachian structural province. In: R. A. Price and R. J. W. Douglas (Editors), Variations in Tectonic Styles in Canada. Geol. Assoc. Can., Montreal, Spec. Pap., 11 : 1 8 1 - - 2 6 1 . Wilson, L. R., 1958. A chitinozoan faunule from the Sylvan Shale of Oklahoma. Okla. Geol. Notes, 18: 67--71. Wilson, L. R. and Dolly, E. D., 1964. Chitinozoa in the Tulip Creek Formation, Simpson Group (Ordovician), of Oklahoma, Okla. Geol. Notes, 24(10): 224--232. Wilson, L. R. and Hedlund, R. W., 1964. Calpichitina scabiosa, a new chitinozoan from the Sylvan Shale (Ordovician) of Oklahoma. Okla. Geol. Notes, 24(7 ): 161--164.