The ammonites of the blue lias

186

THE AMMONITES OF THE

BLUE LIAS.

By L. F. SPATH, D.Se., F.G.S. ReuJIJIlI 29111 Mil", 192 •• RIIIIl

.,11 'II......"" 1924.

PLATE 18.

I. INTRODUCTION. is not generally realised that the ammonite fauna of Lyme Regis is still very incompletely known. This may seem hardly credible to the non-specialist; but to take only the three major" zones" of the Blue Lias here dealt with. it v.~ll readily be found that ·in existing collections neither the zonal ammonites themselves nor many of the species here discussed are represented from the Dorset-Devon coast. Psiloceras planorbis, or at least forms at one time included in that species, are always crushed; the species of Schlotheimia formerly referred to Ammonites angulatus Schlotheim are nearly alwavs fragmentary; and the large examples that used to .be inclu&d in the comprehensive "species" Ammonites btlCklandi are generally far too heavy and embedded in too hard a matrix to be taken away by the ordinary collector. Of other important groups of ammonites, the genera Waehneroceras, Psilophyllites, Alsatites, Agassiceras and Paracoroniceras, to mention only a few, had not previously been known from Lyme Regis. It is to be hoped that Dr. Lang's detailed account of the succession will stimulate further collecting. Meanwhile, the present summary of the Lyme ammonite fauna, offered with some hesitation, cannot be considered as more than provisional. Before discussing the ammonites themselves it may be advisable to review the sub-divisions of the Hettangian and lowest Sinemurian (" bucklandi" zone p. p.) that constitute the Blue Lias. In the ." bucklandi bed" in Oppel's original meaning, seven divisions or sub-zones had previously (Spath, 1922, p. 172) been distinguished; and the uppermost (" Agassiceras ") subzone was further split up into three horizons on a subsequent occasion (Spath, 1923a, p. 84). Comparing the present material with that from Skye, it also appears that Mr. Tutcher's (1918, p. 279; 1923, p. 269) scipionianumzone is capable of subdivision. For only a probable lower horizon with Arnioceras acuticarinatum seems to occur in Skye, whereas an upper portion characterised by Agassiceras colesi (J. Buckman) and Artfioceras nodulosum (J. Buckman) is well developed at Lyme above a condensed representation-in beds 47 to 49-<>f probably the acuticarinatum, gmuendense and meridionalis zones. With the evidence supplied by Dr. Fiege's (1923, p. 91) recent work in Germany, the sub-

IT

THE AMMONITES OF THE BLUE LIAS.

division of the original bucklandi (plus geometricus) bed into the following thirteen hemerre and three ages is thus possible:

i .{ J. 't:l

~~

05

Euagassiceras sp.

g

striaries

~

pseudokridion

~

Arnioceras sp. nov.

}---.

scipionianum

g

......

gmuendense and bucklandi r:!

Q)

u

'S

8

3 rotiforme

colesi {

acuticarinatum gmuendense

I

meridionalis*

charmassei

kridion

rotator

'g {brevidorsale

conybeari

~

longidomus

The species of Arnioceras characteristic of the horizon at the top of the Blue Lias sequence here dealt with, namely, A. pseudo~ kridion sp. nov. is now figured (Plate 18, figs. 4 and 5) to facilitate -correlation of the Lyme succession with, and its checking by, sequences in other areas. In Dr. Lang's detailed list of the beds and on the map published therewith only the comprehensive zones of the first column in the above table were indicated. Even so, on account of insufficiency of material from certain beds, as Dr. Lang points out, the boundaries between the zones had to be somewhat arbitrarily placed. As regards the Hettangian, Rothpletz (1888) subdivided the planorbis and angulata zones into five horizons; but he restricted the term angulata zone to an horizon that Waehner (pt. 3, 1886, p. 199; 1886b, p. 170), before him, had included in his megastoma bed. The term angulata zone, however, if used at all, should be applied to the whole of the Upper Hettangian in Oppel's original connotation. Waehner (pt. 3, 1886, p. 200) considered the megastoma layer to correspond to the zone of Ammonites laqueus and the lower half of the zone • Upper Coro"'a,as .ub-zone in Spath (1922, p. 171)

man ('9,Pa, pp, 273-4).

=

V"eiltgelotiz hemera ? in S. S. Buck-

188

L. F. SPATH,

of Amm. angu1atus of the extra-Alpine Lias. But his Alpinematerial of A. angulatus from this megastoma bed consisted of only three small examples which, like the A. angu1atus of Rothpletz's third zone, are probably immature Waehneroceras and almost certainly not identical with what in this country has generally been taken to be the typical Sch10theimia angulata, namely Wright's figs. 5-6 of pI. 14, (1879 and 1881, p. 318), included by Waehner himself in the synonymy of Schlotheim's species. Haug (1907, p. 954) distinguished a zone of Sch10theimia angulata, with Alsatites 1iasicus, above the zone of A1satites. 1aqueus; but according to the Lyme material so far available Sch10theimia angu1ata occurs considerably higher than A1satites 1aqueus, so that Mr. Tutcher's liasicus zone is probably well justified. Also, at Lyme Regis below the 1aqueus horizon there is a bed with Psilophyllites hagenowi (Dunker) which species had been recognised to occupy a separate level above the "psilo!l-otus zone" so long ago as 1871 (Brauns, p. 181), though it was spoken of as a possible" relic of the marine Trias" still in 1913 (Thompson, p. 170). The laqueus, hagenowi and portlocki horizons would be equivalent to the wider "megastoma zone." Waehneroceras: portlocki is a British species close to W. extracostatum and less advanced than W. megastoma. It seems advisable to include the lower part of the" megastoma zone," with abundant and highly specialised Psiloceratids, in the planorbis zone s. 1. The upper part, corresponding to the " Arietenzone " of Rothpletz~ is referred to the angulatus zone s. 1.; but the marmorea horizon at the top is capable of further subdivision. Unfortunately, the forms of Schlotheimia recently taken as zonal indexes by Lange (1922, pp. 461-]1) are not yet figured. The full sequence of the Hettangian then seems to be as follows :. ~

2 Si

marmorea { stenOrhyncha) Lang . e, germamca 1922 liasicus amblygonia

Iangulata

zo ne (Tutcher I9I8)

f

} Arieten zone

(Rothpletz)

1aqueus

\O.~

~~

-.

hagenowi

.....

Po. 2 ooc, o& ~ (P ril k· -">

t

johnstoni.

.§ eequabile ~

I

angulata zone

(Rothpletz 1888)

THE AMMONITES OF THE BLUE LIAS.

189

The lowest (cequabile) hemera is adopted from S. S. Buckman

(1923, pI. 390.) to avoid the double use of the term planorbis.

The Hettangian stage may thus conveniently be divided into a Psiloceratan age below and a Schlotheimian age above, to replace Mr. Buckman's (1922, p. 13) "Caloceratan." The " Hettangian" zones lately distinguished by G. Dubar (1923, p. 96) should apparently have. been referred to the Sinemurian. Even Alsatites laqueus (Quenstedt), the only non-Sinemurian ammonite quoted, is probably a young Vermiceras (scylla group ?) if one may judge from a cast kindly sent by M. Dubar. It will be convenient to group the ammonites of these eighteen horizons of the Blue Lias into six families, for which the names Psiloceratidre, Angulatidre, Alsatitidl38 nov., Ammonitidre, s. s., Arnioceratidl38 nov. and Agassiceratidl38 nov. will be adopted. The last four, with Arietidre s. s. (as defined below, p. 205) and Oxynotidre Hyatt, form the larger family, " Arietidre " in Hyatt's original sense. The presence of a keel, by itself, is no indication of genetic affinity and it is believed that the fundamental root-stocks of Phylloceratidre and Lyto-ceratidre, via forms like Pleuracanthites, replenished e.g. Alsatitidre. For the very interesting forms intermediate between what had been included in lEgoceras (" Psiloceras " and " ArieJites ") and Lytoceras, Hyatt's family name Pleuracanthitidrewas provisionally adopted (Spath, 1914, p. 356) but discarded as untenable in 1919 (Spath, p. 221). Unfortunately these intermediate forms, notably the various developments grouped in Ectocentrites Waehner, * as well as the radical Phylloceratids and Lytoceratids, are unknown in this country so that there is a deceptive distinctness in the various" families" discussed below. It cannot be emphasised too strongly that the ammonites so far collected in the Blue Lias of the Dorset-Devon coast form -only a smaIl percentage of the total fauna of the horizons here considered, so that the present account is in the nature of a preliminary sketch. Now that the beds can easily be identified and referred to in great detail, workers of sufficient enthusiasm may perhaps be induced to help in the recovery of the often bulky fossil treasures. Further collecting is desirable not only at the cliff section but also at a few inland exposures only a short distance from the coast. For example, during two recent visits to Yawle Quarry, Uplyme (under unfavourable conditions), I was unable to get sufficient fossil evidence to prove the correspondence ()f the beds with tho~e of the coast section. There is room for • Restricted to the Hettangian E. pelers; (Hauer). For I ' Ectocentrt"tfs " Hodostrictus IQUtnstedt) Pompeckj (" Beilr. z. Revis. d. Ammen. d. Schwab. Jura." Ja}""h. V". Val. N(l/u,I<. ",'il,ttemb., vol. xlix.,1893, p. 357, pI. v., fig. 6) of the Num~mah~ Marl~. the new genus Bolcob1cceru is propo~ed; also COlmol)'tocera. gen. nov. for .. Ectc.untrt/rs" CR,,'t a'''J BonarelIi ("Cefalop. SinerouT." Pal. lIal., yd. v. (1900), p. 70, p. ix., fig.3. B.M. 1\0. (8473, Morena COli.).

190

L. F. SPATH,

nearly the whole of the Hettangian, and the ammonites from this quarry include Schlotheimia aft. depressa (Quenstedt) which was picked up loose but probably did not come from below at least the liasicus zone. According to Mr. Cameron the top of the Rhretic (now hidden by talus) is 4-6 ft. above the floor of the quarry and about 15 it. higher is a prominent band (" Glassbottle," but not Dr. Lang's Bed 47). I thought I could make out the four "Conspicuous Limestones" of Dr. Lang in the next 15 ft., and poor impressions of what may have been Psilophyllites and a doubtful Alsatites in a limestone above these shales seemed to confirm this exact correspondence with the beds of the coast. But Mr. Cameron found '.' A. angulatus" (perhaps a Schlotheimia of the prometheus-group to judge by his collection, now in the posses~ion of Dr. Wyatt Wingrave) 6 ft. below" Glass Bottle," which is far too low (even if the "White Lias" is not Rhretic) unless there be -considerable gaps. The succession at Uplyme is well worth careful examination. The Hettangian sequence in Normandy, which may not include the lowest beds (Lemoine, 19II) also requires investigation in greater detail before exact comparison can be made. Interesting from a palreogeographical point of view is the occurrence of Psiloceras planorbis 30 miles south of Eddystone Lighthouse, where it was dredged from a depth of 80 metres (Kilian and Blanchet, 1923). The identification, of course, may be at fault, and at Lyme the similar young of Eparnioceras of the semicostatum group occur in a limestone. In any case there was a considerable westward extension of the" Jurowessexian Channel," as drawn in Map A of the excellent chapter on "Chronology" in Mr. Buckman's Type-Ammonites (1923, p~ 52). I am indebted to Dr. W. D. Lang for the opportunity to deal with his ammonite material and to Dr. Wyatt Wingrave of Lyme Regis for permission to use his extensive collection and for his ever ready help. Acknowledgments are also due to Prof. H. Salfeld and Dr. H. Schmidt, of Gottingen, to Dr H. Frebold, Hanover, Dr. K. Fiege, Essen, and Dr. J. Pia, Vienna, for sending specimens or facilitating their exchange or for kind information regarding their recent work on the Lias. II.

FAMILY' PSILOCERATlDlE HYATT emend.

The poor impressions of Psiloceras in bed HZ9 include what is probably the smooth, e volute , Ps. sampsoni (Portlock) and a ribbed species of the group of Ps. plicatulum (Quenstedt, 1883 ; type pI. i., fig. 9) and Ps. plicatum (Quenstedt; type = Ps. plicatulum, Pompeckj, 1893, p. 212, pI. 6, figs. I, Ia).* No • Hyatt's (x889,'Pl. L, figs. 3-4), P.I)11o:l'l'as planorbi,'t, var. 1eve is intt'nneoiate between Ps. Ps;!onotum (Quenst~dt) and Ps. plica/ulum '.Quenstedt). Re~"Il.s's (1879. pI. I. fig. 10) fonn may be renamed PstlQct'tas reynen. nom. nov.

THE AMMOXITES OF THE BLUE LIAS.

I9I

example of Ps. planorbis (Sowerby), the genotype, has been examined, and the only form available from Uplyme, probably from the Caloceras bed, may be compared to Ps. nicarium, Holland (1900, p. 501, p. 9, fig. 3). This resembles a form from the" Rummel Bed" (johnstoni zone) of Barrow-on-Soar in the Tomes Collection (B.M., No. CI7002). All these species belong to the typical Psiloceras with simple suture-lines. Dr. Fiege (1923, p. 64) thinks that their inner whorls should show suturelines of the calliphyllum type to justify their description, by Neumayr, as simplified; but the planorbis and calliphyllum groups are probably successive developments of the same Monophyllitid root-stock, and simplification in the planorbis branch, is distinct already in the young. Similarly, in some species of Psiloceras, costation first appears on the inner whorls and this cannot be accepted as evidence of recapitulation of some Caloceras-like ancestor. Specimens of the genus Caloceras have so far been found only in beds H 43 and 44. Caloceras intermedium (Portlock) is the commoner species in the latter, occurring mostly as body-chamber fragments; but i;he preservation of the forms in H 43 (Caloceras sp. ind., C. of belcheri group) is very poor. The examples of Caloceras from Uplyme are in a better state of preservation and include C. intermedium (Portlock), and a closely costate variety, C. belcheri (Simpson), C. giganteum, sp. nov. (d. Ammon. laqueolus, Reynes; non Schloenbach, pI. 7, figs. 3-5 only, L.F.S. No. 1539) and C. wrighti, sp. nov. (Aegoceras belcheri, Wright, non Simpson, pI. 19, figs. 1-2 only). This last species differs from Caloceras torum (d'Orbigny) the genotype, in the closeness and early degeneration of its costation. Psilophyllites hagenowi (Dunker, 1847), which occurs abundantly in bed H 67a, fifteen feet above the Psiloceras shales, is a very reduced type of Psiloceratid (but not of Psiloceras planorbis as Hyatt (1889, p. 124) thought) with almost ceratitic sutureline. There is a feeble tendency to develop notches at various parts of the lobes and saddles, but they never become definite incisions, except in the principal lobe (L). Examples from a derived block from the Holderness Coast (B.M., No. CI7873) an 1 from the typical locality Exten, near Rinteln, Hanover, are here figured (Plate 18, I b-d) for comparison with the crushed Lyme example (Plate 18, Ia) and the specimens figured (as Schlotheimia d. hagenowi) by Dr. A. E. Trueman (1922) from the lower part of the "angulata zone" of La vernock; also the figures given by Schloenbach (1865), Terquem and Piette (1865) and Quenstedt (1883, pI. I, fig. 18). The suture-lines here figured are interesting because, unlike Psiloceras of the planorbis group, Psilophyllites first develops incisions in the lobes and not on the saddles, a detail reminiscent of the suture-line of immature Monophyllites (Spath, 1914, p.

L. F. SPATl'I,

357, text fig. ~h). The young of PsilophyUites was indeed, Oll a fonner occasIOn (Spath, 1919, p. 34) described as looking like a Palreozoic P,ono,ites, and it is interesting to compare in this connection the asymmetrical suture-line of Asaphoceras gen. E

~

~IJ

I~C; E

E

~e I

E

f

~ I

FIG. I2.-Psilophyllites hagenowi (Dunker). Hettangian, hagenowi bed. a. Suture-line of Holderness Drift example (B.M., No. C17873) figured .plate 18, lb, sho\ling variability of minor incisions on opposite halves. b. External saddle of an earlier suture-line of the same example. c. Sulure-line of a fragmentary example from same block, showing less ceratitic saddles. dog. Suture-line of Exten examples (See Brauns, 1871, p. 181). d = diameter of 13 mm. (pI. 18, fig. Id) .. e = pI. 18, fig. IC. ; f, g. = smaller example, at diameters of 10 and 8 mm. [E = external lobe; I = internal lobe).

nov. (for " Amphice,as" apenninicum Fucini, Riv. ltal. Pal., vol. xvii., 19II, p. 47, pI. 3, figs. ~-c), probably a reduced member of Seguenziceratida fam. nov. It is also to be noted that-unlike PsiloceTas again-Psilophyllites has no suspensive umbilical lobe, a feature on which stress

THE AMMONITES OF THE BLUE LIAS.

has been laid by Mr. Buckman (1898, p. 44S) but which is prob.ably of little consequence (Spath, 1914, p. 3S2) and, in any case in Psiloceras, is not developed until a comparatively late stage as is well shown in the suture-development lately published by Dietz (1923, p. 396, fig. 12). The reduction of the internal 10 be in the suture-line of Psilophyllites as compared with that of Psiloceras or especially Parapsiloceras, is important in view of the opinions on the classificatory value of this lobe lately expressed by Prof. Salfeld (1919, p. 8, 1923, pp. 4-6), who put the primitive" Psiloceras in the vlcinity of Lytoceras. How reduction may result in a .. lituid " internal lobe, however, is well il~ustrated also by the suture-line of the variety of Hysteroceras bmum (Sowerby) from the Gault, lately figured by the writer"(Spath, 1923c, p. 10, fig. 1 h). Lange (1922, p. 471), who introduced a new generic name for this group, having overlooked Psilophyllites (Spath, 1914, p. 3S1) considered it probable that P. hagenowi .occupied a separate horizon between the johnstoni zone and his " Proarietites" bed. The involute, high-whorled Discamphiceras of Middle Hettangian age is unknown in this country, as are the equally late Euphyllites*-probably an independent development of the phylloceratid root-stock-and the very evolute Parapsilo.ceras, which occurs just above the calliphyllum bed (about portlocki horizon of this paper). Parapsiloceras is close to Pleuracanthites, but conveniently included in PsiloceratidtE, also Franziceras. The last is connected with Psiloceras rahana (Waehner) by .. Psiloceras" crebricinctum (Waehner) and a new species of Franziceras from Chadbury, Worcestershire (B.M., No. C6203, Slatter Coll.) which is more closely costate than F. ruidum S. S. Buckman, from Radstock. On the other hand, Waehneroceras tomesi sp. nov. ( = Psiloceras n.f. indo in Waehner, loco cit., pt. iii. [1886], p. 20S, pI. 27, figs. 4a, b) represented by an example from Hinton Hill, Warwickshire (B.M., No. C16S37, Tomes Coll.) leads from F ranziceras to Waehneroceras anisophyllum (Waehner) and resembles also some New Zealand Psiloceras (Euphyllites?) spp. described by the writer (1923b, pp. 288-9). The inclusion in the family Psiloceratidre, of a sub-family lEgoceratinre (Dietz, 1923, p. 47S), or vice versa, of Psiloceratinre in a super family lEgoceratidre (Zittel, 1921, p. SSS) is not justified. The earliest lEgocerates yet studied (Microderoceras, Hyatt, fam. Deroceratidre) are independently derived from the ·original Lytoceratids (Spath, 1923a, pp. 82-4; Frebold, 1923) and are not descended from Psiloceras. In addition to DerolytoSpath and lEgolytoceras Spath ceras Rosenberg emend. ( = .. Geyeria," Fucini, type: "Lytoceras" serorugatum [SturJ oj

• Grnnl(>('totype: Eu/)1Jyllites struckmanni, \\'aehnt>r, loco cit., pt. viii. (1898), p. 170, pL xxii.

~gs.

"a-
L. F. SPATH,

Fucini) two of the stocks that produced and replenished " lEgoceratidre" are represented by Peltolytoceras gen. nov. (genotype: Ectocentrites giordanii Bonarelli, loco cit. 1900, p. 75. pI. 10, fig. 4, B.M. No. C8471) and Tragolytoceras gen. nov. (genotype: Lytoceras altecinctum [Hauer] Bonarelli ib. p. 70, pI. 9, fig. I, B.M. No C8480). Unfortunately only their modified descendants are found in north-western Europe, so that these important transitional forms have been neglected in favour of a hypothetical" primitive radicaL" Prof. Salfeld (1923, p. 30) who, independently from the writer, came to the conclusion that the persistent root-stocks of Phylloceratids and Lytoceratids (Salfeld's "Konservativstamme ") continuously produced trachyostracous offshoots, lately considered Prodactylioceras Spath (=group of Amm. davoei ]. Sowerby) and Cicatrites Anthula to be homceomorphous Lytoceras-derivatives; Frebold (1922) even put" Amaltheus" lenticularis (Young and Bird) into the genus Tragophylloceras. The descendants of Prodactylioceras tend to reduce their suture-lines and some " Amaltheids " specialise in complex oxycones, but biological and geological order should, and do, agree unless vision be limited by experience of merely local and unrepresentative faunas. Of course, it may be necessary to assume an inverted "geological order" if our views of the biological order of Ammonites are to continue to be governed by discredited " laws" of recapitulation and omission of hypothetical stages. Equally untenable seems to be the assumption that the more specialised forms arrived in "shallow water" hemerre (i.e .• presumably many thousands of years) before their more primitive fore-runners. The well-worn objection of the incompleteness. of the geological record, of course, always applies, but cuts both ways. It seems to the writer that objective examinations of the geological occurrence of the successive time-members of given series of ammonites, i.e., careful zonal collecting in suitable areas, will do more for a rational classification of these organisms. than fifty years of personal biological speculations have done.

III. FAMILY ANGULATID1E HYATT. This family includes the genera Waehneroceras Hyatt, SchZotheimia Bayle, Sulci/erites Spath, Charmasseiceras gen. nov. (proposed for lEgoceras charmassei d'Orbigny sp., Wright, loco cit., pI. 20, figs 1-3, B.M. No. C1915) and Boucaulticeras gen. nov. (proposed for JEgoceras boucaultianum d'Orbigny sp. in Wright, loco cit., pI. 18, fig. I, B.M No. C3125). Pseudo8chlotheimia gen. nov. (genotype: "Schlotheimia" densilobata Pompeckj, loco cit. [1893], p. 242, pI. vii., fig. I) of the raricostatus zone, is also doubtfully included in the present family.

THE AMMONITES OF THE BLUE LIAS.

There is, in the British Museum, a fine specimen of a new compressed species of Pseudoschlotheimia (No. CI946) which was labelled by Wright "A. beaumontianus, d'Orbigny, Gault. Folkestone." Here the groove of the inner volutions, on the last half of the outer whorl, is replaced by a narrowly tabulate venter, as for example in Placenticeras pseudoplacenta Hyatt. It appears to be a specialised offshoot of either Boucaulticeras or" Angulaticeras "( = lacunata group of the oxynotus zone). JEgoceras diPloptychum Waehner (loc. cit., pt. i. 1882, p. 84. pI. 8, fig. I) with secondary ribbing, included by Hyatt in Waehneroceras, must also be referred to the family Angulatidre and the new name Kammerkarites gen. nov. is now proposed for it. It is a specialised offshoot of Waehneroceras, quite distinct from the iapetus group on the one hand that leads to Schlotheimia and the megastoma group on the other with a tendency in the direction of the Alsatitid genus PseudfEtomoceras. The Lyme examples of Waehneroceras are poorly pres.erved. Moreover, the inner whorls of the typical forms of the group of W. extracostatum and the almost identical W. portlocki (Wright)" or of -W. eurviornatum (Waehner) resemble Schlotheimia even when well preserved. A form close to the last species and to W. haploptychum (Waehner) is before me in a typical example (B.M. No. CI7825, Tomes CoIL), probably from Chadbury, Worcestershire, and apparently species like Psiloceras harpoptychum Holland, with slightly contracted venter, form transitions to Psiloceras of the plicatulum group. A number of specimens collected by the writer in bed H 67, are oyster-incrustations, but the regular ornamentation is often well shown, resembling that of W. extracostatum as depicted by Waehner (loc. cit. [1882], pI. I, fig. 2) or of W. subangular~ Oppel sp. (to which may belong the W. sp. indo of bed H 57) which is close to the type species W. tenerum Neumayr. The larger impressions found in bed H 67d are characterised by an almost smooth outer whorl, wherefore they are compared toWaehneroeeras of the megastoma type., The probable Waehneroceras from bed H 71 are not identifiable specifically, but include fragments still resembling W. subangulare al\d perhaps W. baltzeri (Epstein, 1908) of the portlocki beds. No pyritic Waehneroceras were observed in place; but there is, in the collection of Dr. Wyatt Wingrave, at Lyme Regis, a specimen of W. ia:petus sp. nov. (= JEgoceras catena Wright non Sowerby, loe. c~t. 1880, pI. 19, figs. 5-7) said to come from West of Lyme. (The specimen listed as W. d. iapetus, bed H 67b, is merely an impression). Its mode of preservation is similar to that of the well-known Barrow-on-Soar examples, which come from a horizon separated from the Rummel Bed (johnstoni zone) above referred to, by 15ft. of GrYPhfEa beds (Woodward~ 1893, p. 169). The suture-line of the Lyme specimen is figured

196

L. F. SPATH,

in fig. 13a and the development of a Barrow-on-Soar example of W. iapetus is given on pI. IS, figs. 3a, b and figs. 13b-f. It is interesting to find constrictions in the young and asymmetry of the extemallobe, as in Psiloceras, and comparison should be made with the development of the suture-line in Psiloceras of the planorbis group, as figured by Dietz..

a b· l • g

FIG. 13. Waehneroceras iapetus sp. nov. Hettangian (laqueus-hagenowi hemerre). Asymmetrical external suture-line ( X 4) of an example 3aid to be from Lyme (Coll. Dr. Wyatt Wingrave). Development of suture-line from a Barrow-on-Soar example (Coil. L.F.S. No. 893) at diameters of 18. 9. 7. 4 and .5 mm. resp;ctivply. Internal suture-line of an example 10 the Blake Coll. (B.M. No. CI9183) probably also from Barrow. (E = externallob-:. I = internal lobe, M = median line of periphery).

Holland (1900, p. 499) wrongly united Wright's form with Waehneroceras subangulare (Oppel) and Mr. Buckman (1906, p. 236) doubtfully referred it to Schlotheimia aqualis (Simpson), but Blake's (Simpson's ?) type of this species, referred to by the late G. C. Crick (1922, p. 274) is a finely costate form, close to

THE AMMONITES OF THE BLUE LIAS.

197

the less dwarfed S. prometheus (Reynes, 1879, pI. 2, figs. 16-17) and less advanced than Schlotheimia gallica S. S. Buckman. In all these the Schlotheimia groove is already developed, but only on the inner whorls, whereas Waehneroceras iapetus and its allies of the stricklandi-acuticosta group never have truly sulcate venters. These last are probably of hagenowi and laqueus age. In the liasicus zone above, by means of the later forms transitional between Waehneroceras and Schlotheimia, three horizons may perhaps be distinguished:liasicus

PhaniX { gallica prometheus.

Examples of what I (1922, p. 176) was in the habit of inclUding in a comprehensive species Schlotheimia thalassica (Quenstedt) come from bed H 91, i.e., from the liasicus zone. The type of Quenstedt's species is the example depicted in his pI. 2, fig. 5. but though the sectional view is not shown, it may be taken to be at least as wide, peripherally, as that of S. moreana, and not acute. Pompeckj (1893, p. 228) wrongly united this typical Ammon. angulatus thalassicus (also the form figured by Quenstedt in fig. 4 of the same plate) with Schlotheimia depressa (Quenstedt), topotypes of which, agreeing with Quenstedt's fig. I of pI. II., I have before me. It is clear that the Lyme form from bed H 91 cannot properly be referred to Schl. thalassica and the new name Schl. simills sp. n. is therefore now proposed for it. The subtrigonal whorl-section and projected peripheral costation are characteristic, and a small fragment, with the suture-line well preserved, is illustrated on pI. 18, figs, 2a, b. A comparable example from Harbury cutting in the Tomes Collection (B.M .. No. C16823) is marked " Lima Beds." Schlotheimia pseudomoreana sp. nov. (= lEgoceras angulatum Schlotheim [= Amm. moreanus, d'Orbigny] in Wright. loc. cit., pI. 17, fig. I only, B.M. No. C2227) differs from S. similis in having a slightly less acute periphery, less trigonal whorl-shape and less projected and fewer costre, but Wright's drawing is not of the natural size, as stated, but reduced to two-thirds of the diameter, and moreover not very accurate. The peripheral view (pI. 17, fig. 2) also does not belong to the same specimen, as stated. This probably accounts for Mr. Buckmari's acceptance of Hyatt's identification of Wright's form with Ammon. colubratus Zieten (1830). Schlotheimia depressa (Quenstedt), S. princeps S. Buckman (the genotype), S. moreana (d'Orbigny), and S. extranodosa Waehner, are other forms of this group occurring in the horizon of S. marmorea ; but S. phmnix sp. nov. (=Amm. angulatus [pars] Reynes, pI. 4, fig. 6 only) is somewhat intermediate between the similis and

198

L. F. SPATH,

thalassica-depressa groups, as it is intermediate in stratigraphical position. The typical Schlotheimia of the angulata-striata group, <>ccur abundantly in beds 14 and IS. Wright's example of plate 14, figs. 5 and 6, identified with Schlotheim's Ammon. angulatus by e.g. Pompeckj and accepted as such by most recent writers, well illustrates this group, chara~terised by the persistence of the typical ornamentation and periphery to a large diameter. It is interesting to note that the highest Hettangian Schlotheimia are the most typical and that their immediate successors of the group of the gigantic S. greenoughi (J. Sowerby) represent probably the acme of Schlotheimid development. The Schlotheimia characters first appear on the inner whirls of Waehneroceras of the extracostatum group, become more pronounced on the inner whorls of the groups of W. iapetus and Schlotheimia prometheus and persist to the outermost whorls only in the late angulata group. A large example of a Schlotheimia allied to S. greenoughi, but slightly more closely costate at the same diameter, though with smooth outer whorl, has lately been found by the writer west of Lyme, unfortunately not in place. Like S. greenoughi this example adumbrates the later gigantic Charmasseiceras, and this species, indeed, was described as being allied to " S." charmassei (Spath, 1915). They may be developments of the group of Schlotheimia ventricosa (Sowerby) rather than of the somewhat similar group of S. thalassica which also tends to sharpening of the periphery. An example from bed 14, is identified with Wright's figs. 3 and 4 of pI. 17, here renamed S. quadrata, n.nov. One 'Of the specimens compared to S. extranodosa (No. 4195) is slightly more involute than fig. 7a of Waehner's pI. 20, the other is a large fragment of an outer whorl that has the peripheral aspect of examples of S. exoptycha (Waehner) from Redcar, Yorks {L.F.S., No. 701) and of S. aff. depressa (Quenstedt) from Filder, Wurtemberg (B.M. No. 22184). Both S. extranodosa and S. exoptycha are recorded by Waehner from the marmorea zone, but the last species has not yet been found at Lyme. An ex~ ample of S. aff. complanata, v. Koenen (L.F.S. 449) was found loose, but probably also came from beds 14 or IS and other examples, not found in place, include S. aff. moreana (d'Orbigny), S. sp. nov. ? aft. pseudomoreana, n. (B.M., No. CI7980), S. sp. aft. depressa (Quenstedt) (B.M., No. C6II4), S. colubrata (Zieten) (B.M., No. 39720). Charmasseiceras charmassei (d'Orbigny) was formerly left in Schlotheimia (Spath, I923a, p. 79) and Ammon. boucaultianus d'Orbigny, now Boucaulticeras, was included in Sulciferites but really forms a highly specialised off-shoot, probably of Charmasseiccras, and antedates Sulcifcrites. This more or less micro-

THE AMMONITES OF THE BLUE LIAS.

199

morph genus, distinguished from Charmasseiceras by its sharp -costation, according to a Weston-on-Avon example (B.M., No. C16505, Tomes CoIl.) marked" with Amm. brooki," tends to develop close and single costation on the body-chamber and the ribs lose their peripheral interruption and are connected across the ventral area by forwardly-directed chevrons. The crushed examples of Charmasseiceras from beds 42-44 are referred to Ch. charmassei and allied young or indetermined species. The Redcar example figured by Mr. Buckman (1906, pI. 10, figs. 19-20) resembles some of the Lyme specimens; one example is considerably more coarsely costate and may be referable to Ch. posttaurinum Waehner sp. (lectotype: pI. 26, figs I a-d, loco cit., pt. iii., 1886). This is certainly not identical with the Luxemburg example figured by Chapuis (1858), as Waehner held, and the new name Ch. strassenense n.n. is now proposed for it. Ch. compressum (Quenstedt) according to Wurtemberg examples before me, is not identical with Ch. charmassei, as Pompeckj thought (1893, p. 231) and Ch. angulajoides (Quenstedt) is transitional from the true Schlotheimia to C harmasseiceras compressum. Specimens of Charmasseiceras comparable to the Lyme forms ,occur at Fretheme, Gloucestershire (Lucy and Tomes collections in the B.M.) according to Mr. Richardson's (1908, pp. 140-1) account, about 20 feet below Arnioceras bodleyi. At Lyme, the maximum development of what may be A. bodl~yi is considerably higher above the beds with Charmasseiceras, but this may be explained by the absence of certain beds at Fretheme ; for even at Lyme there must have been condensation apparently of the acuticarinatus, gmuendense and meridionalis faunas into the pyritic seam at the top of "Glass Bottle" (bed 47). Ch. charmassei may then be taken to be most abundant in the lower part only of the .. bucklandi zone" (of the map) whence the Survey record large" Schlotheimia charmassei " (bed 41 in Dr. Lang's list). Wright's figured specimen and a number of examples seen in loose blocks, some of gigantic size, may thus be assumed to have come from the limestone bands 37, 39, 41 and 43. Charm:1Sseiceras d'orbignyi (Hyatt) and the closely allied Ch. hercynicum n. nov. (= Schlotheimia d'orbignyana Schmidt 1914, pI. 7, fig. 2, non Hyatt) are probably later than Ch. charmassei. At least at Bengeworth, near Evesham, Wor-cestershire, and Stockton, Warwickshire, they are associated with Epammonites, Megarietites, Eucoroniceras, and Ammonites (s. s.) of the meridionalis zone. A finely costate specimen, (L.F.S. 455) found loose on the beach west of Lyme belongs to this group of Charmasseiceras, but the periphery is more like that of Ch. charmassei. The .. Schlotheimia charmassei" of Dubar's (1923, pp. 81, 92.

200

L. F. SPATH,

97) Hettangian horizons 2 and 3, according to his casts in the British Museum, are probably Charmasseiceras, but too immature for exact identification. ]oly (I908, p. I32) also recorded" Schlotkeimia charmassei" as a Hettangian fossil. The involute Boucaulticeras, specialising in ornamentation of a 'very distinct type· has hardly a feature in common with Charmasseiceras, except possibly the shape of the external saddle of its suture-line. The later dwarf-forms of Sulciferites have a simple suture-line and show more resemblance to Schlotheimia ventricosa (~owerby) Waehner than to young Charmasseiceras of the posttaurinum-scolioptychum type, but one of Dr. Lang's (fragmentary) specimens of "Sulciferites" (No. 6269) from the top of bed 73k shows resemblance to Boucaulticeras. IV.

FAMILY ALSATITIDJE nov.

Since Hyatt (I889, p. 54) subdivided his family Arietidce into three parts or stocks, the Psiloceran, the Plicatus and the Levis stocks, comparatively few new Lower Lias faunas have been discovered and our knowledge is stm far too incomplete to attempt the construction of a genealogical tree, after the manner of Hyatt's Summary Plate I4. It is quite certain that Psiloceras pllcatum did not produce the "vermiceran series " (as distinct from a coroniceran) and that "Psiloceras leve" did not develop into Arnioceras or "Agassiceras" as Hyatt held. t The complexity of the interrelations of the various members of the "Arietidce," however, is as yet very incompletely realised, also their connection with the fundamental Phylloceratids and Lytoceratids which must be held to explain the numerous cases of "convergence." Of these radicals only a few more or less unconnected groups have so far been described and such transitional members as Euphyllites or Pleuracanthittst are still more difficult to place in view of our lack of exact information and in the absence of careful zonal collecting in those areas where alone the fundamental stocks persisted. A subdivision of the family Arietidce, which has now become necessary, cannot then proceed on the lines laid down by Hyatt.§ Mr. Buckman (I898, p. 45I, table II.) divided the various genera included by Hyatt in his family Arietidce into two groups, namely, Psiloceratidce, comprising such arietoid genera • The 'example of "ScMalhti"'... bOllCIIIlI/ia..,, " figured by Bonarelli (" Cefalop, Sineonur. dell, Apinnin. Centr." Pal. Ital., vol. v. (1900), p. 68, pI. viii.. fig. 10. B.M. No. C3474. T. Morena Coli.) has early whorls with grooved periphery. like PSe14dolChlolh,i""a. t The choice of such late forms as A,."ioc.ras s""icostalll'" and Cymbiles [" Agassic...","] la{wgatu& as radicals is, of course, unfortunate, but it will not be necessary, at this date, to correct the numerous errors in Hyatt's work. : LJtotropit-. gen. nov. (for Ec/octftlritlSfllc,,,;;, Bonarelli.loc. cit. (1900). p. 72, pI. x .• fig. 2. B.M. No. C847'). in appearance almost like a constricted Paracaloe....... represents a later group of this type. $ The inclusion by Dietz (loc. eit 1923. p. 489) of Ophioctt"s. Hyatt (" EcMoctt'a..... Bayle) in h,s family Arietitidal (" Arietid.. " on p. 478) shows that classification according to the divisions of the umbilical lobe Is not only Impracticable but also cannot be natural.

THE AMi\lOXITES OF THE BLUE LIAS.

201

as Tmcegoccns, * and Arietidce, restricted to Hyatt's remaining genera and j'lcluding Coroniceras, Hyatt's" type-genus" of the family. From Psiloceratidce, as understood by Mr. Buckman, Angulatidce have since been separated as an independent family, and for the arietoid stock to which Tmcegocerast belongs, the writer used the term Caloceratidce, though since" Caloceratidce " was originally (Buckman, 1906, p. 233) proposed as a substitute for Psiloceratidce, and is a synonym of the latter, it cannot be employed. The new family Alsatitidce is therefore now proposed for the genera Paracaloceras, Pseudcetomoceras and Tmcegoceras that were included in this family "Caloceratidce (ex Psiloceratidce)" (Spath, 1923a, p. 77) and in addition to Alsatites itself ( = Proarietites, Lange 1922) the genera Pseudotropites Waehner and Canavarites Hyattt also belong to'his group. It is improbable that this assemblage is truly monophyletic and Alsatites itself may include. on the one hand, forms derived from Psiloceras, through the tortilis-subliasicus group of Caloceras, and on the other derivatives of Parapsiloeeras sublaqueus \Vaehner, and of Pleuracanthites. Yet the proaries and liasicus groups of Alsatites are so similar in all ch~.racters that their retention in this one genus is permissible, if we are not to miss the principal object of all systematic nomenclature. Arietites nigromontanus, Gumbel sp. (Waehner, 1886, pt. 3, pIs. 24 and 25) and Ammonites laqueolus Schloenbach (1865, pI. 26, figs. la, b) though representing separate offshoots, may also provisionally be included with Alsatites, but a different group of Caloceras (johnstoni group), though typically specialising in large size, probably gave rise, via Arietites orthoptyehus, Waehner (pt. 3, 1886, pI. 27, figs. 2 a-d only) and its allies, to a development generically distinct from Alsatites, namely, the group of Arietites prcespiratissimus and A. spiratus Waehner and Amm. delmasi (Reynes) (Gyrophioceras gen. nov., type: Arietites prcespiratissimus, Waehner, pt. 4, 1886, pI. 36, figs. 2 a---e). Alsatites, probably also Paracaloceras. produced similar "Vermiceratids" but the other genera of Alsatitid;e had no progeny. The Lyme forms of Alsatites, so far seen only in beds H69 and 71, agree more with A. laqueus (Quenstedt) and the forms of the same species figured by !{eynes (1879, pI. I, figs. 25-28, pI. II, figs. 1-10) than with the Mediterranean group of A. proaries (Neumayr) in which the costce are more crescentic. One crushed example (5602) in the coarseness of its ribbing, suggests comparison to Caloeeras tortilis (d'Orbigny) below or to Alsatites liasicus (d'Orbigny) above, but its periphery is not shown. The latter species occurs at Keynsham (Tutcher, 1923• • Ahatius IHau~, 1894) was left by Mr. Buckman in C"wc...as (p. 461). t Still included in PsiJoceratinre by Zittel (1921, p. 555), and (doubtfully) by Dietz (1923, p. 475). l..ukadiella, Renz, is an Upper Liassic Hildoceratid, not a subgenus of X.tIlgoe.....,. : Hyatt (1900, p. 577) included P"udot'OPites and ea_,iles in ZIt'Cllth"_, but (ou p. 575) mentioned a family" Pseudotropitid",'"

Paoc. GEOL. Assoc., VOL. XXXV., PART 3, 192+

14

202

1. F. SPA'IH,

p. 274), but has not yet been found at Lyme or in Glamorgan (Trueman, 1922, p. 280). A fragment of Alsatites laqueolu5 (Schloenbach) in the collection of Dr. Wyatt Wingrave, is from the Yawle Quarry, Uplyme. V.

FAMILY AMMONITIDJE

5.5.*

As Alsatites cannot be traced back to a single species of Caloceras, so Vermiceratids, the earliest true Ammonitids, are derived from various Alsatitids. Alsatites itself typically still has a high external lobe, though the family Alsatitidre includes forms in which dependent umbilical lobes are already accompanied by deep ventral sulci. The transition to the low external lobe of other genera of Alsatitidre, unfortunately unknown in North-West Europe, is shown in certain examples that Waehner included in the" variable" species A. proaries itself. In Ammonitidre s.s. the characteristic Arietid suture line becomes more or less definitely established and only in the Vermiceratids, subdivision of which is as yet somewhat provisional, the lateral lobe may still be deeper. than the external lobe. The family is taken to include Vermiceras(genotype V. spiratissimus Quenstedt sp.) which is fairly late and according to Dr. Fiege's researches derived from V. scylla (Reynes) with indistinct peripheral sulci. This group is genericaJl.y different from Metophioceras gen. nov., proposed for Ammonites conybeari J. Sowerby (1816, vol. ii., p. 70, pI. 131, B.M., No. 43971, a species characterised by compression and a high keel persisting to a large diameter). Metophioceras develops peripheral nodes already at a lower horizon and probably gave rise to Coroniceras (genotype Ammonites rotiformis J. Sowerby), Arnioceratoides, and Protocymbites, in addition to the later Ammonites s.s. and Megarietites, Epammonites, Eucoroniceras and Paracoroniceras. Bonarelli (1900, p. 58) took as type of Coroniceras Zieten's Amm. kridion, but Mr. Buckman two years previously (p. 459) selected Amm. rotiformis (Sowerby), though in 19II (p. vi.), quite unjustifiably, he attempted to substitute as genotype Amm. coronaries Quenstedt. Meek (1876) considered Coroniceras Hyatt to be synonymous with Ammonites s.s. which he was the first definitely to restrict to "Amm. bisulcatus" Bruguiere. This species included all the figures in existence at the time Meek wrote and was fixed by Hyatt's Coroniceras bisulcatum (1867, p. 77), one of the original" syntypes," and my selection of d'Orbigny's oldest identifiable figure, quoted by Hyatt. Lang's original specimen from the Hartz mountains, very badly drawn, to judge • Owen, r836, emend. Meek 1876. Hyatt substituted Arietidal (r870) for Discoceratid", (r867) which was put = A,ietites, Waagen. Hyatt (r889) regarded Co,onice,as as lhe type genus of Arietidre, but since this included Ammonites, Bruguiere emend. Meek, it seems advisable to "elect the original family name Ammonitidre for the uewly restricted assemblage that includes both Ammonites 5.S. and Coroniceras, but DC.t A,ictites 5.S.

THE AMMONITES OF THE BLUE LIAS.

203

by the Harzburg fauna, certainly is not identical with Sowerby's Amm. bucklandi, but may be congeneric with d'Orbigny's Amm. bisulcatus. The genus Ammonites s.s. then is here taken to apply to a stock somewhat intermediate between. Epammonites and Megarietites and with these genera restricted to the ,gmuendense zone of Mr. Tutcher, i.e., well above the "bucklandi zone." The earlier genera of this family are abundantly represented from Lyme, but the few later forms apparently are confined to a condensed seam above" Glass Bottle" (bed 47) ana 'in any ,case not nearly enough collecting has yet been done on the Dorset-Devon coast to enable us to give a representative list of the species actually occurring. The forms of the conybeari zone are all referable to Metophioceras and include M. sp. aff. conybeari (Sowerby) from" Top Tape" (bed 29) where it is associated with numerous other forms of which only a few have as yet been secured. These include M. janus sp. nov. (= Arietites conybeari Wright, non Sowerby, pI. 2) and allied forms. Associated with M. janus in bed 24c is a new, unnamed form, with closer and more rectiradiate costation, differing from M. ccesar (Reyn~s) in its depressed whorls. M. rouvillei (Reynes) which occurs at Redcar, Yorks., .and M. 0phioides, before me from Stockton, Warwickshire (B.M. No. C2340I and 23403) and the Lima Beds of Witnush, Glos. (B.M. No. CI6825), have not yet been found at Lyme. Somewhere in the lower half, probably, of the conybeari zone, there occurs a fauna, known to the writer only fromloose blocks, ·characterised by the abundance of M. gracile, sp. nov. (=Amm. conybeari, d'Orbigny, non Sowerby, Pal. Fran<;. Ter. Jur. 1844, pI. 50).* This closely costate form is associated with M. ccesar (Reynes) and a poor impression of a caprotinus-like form of Metophioceras, also with what appears to agree with M. deffneri (Oppel) and M. brevidorsale (Quenstedt, 1883, pI. 7, fig. I, lectotype). What is probablythe true M. bonnardi (d'Orbigny) identified by Reynes with M. deffneri and recorded from York.shire by Blake (1876, p. 284) as" Arietites conybeari," also belongs to this brevidorsale assemblage. Hyatt (1889, p. 158) mistook M. conybeari for Arietites of the plotli group when he stated it to be associated, in the collection of the Museum of Comparative Zoology, upon the same slab with Amm. birchi. He also included in the synonymy of " Vermiceras" conybeari, with other distinct species, Wright's figs. 1-3 ·of pI. II, renamed by the writer Arietites pseudobonnardi. Similar forms, generally confused with " Vermiceras," e.g. Amm. landrioti, d'Orbigny, the group of "Vermiceras" ultra.spiratum Fucini, and probably Amm. latisulcatus longicella * In II Second Mongrel" (bed 21), from which the Survey recorded Amm. con'Ybeari, small ,examples of M etophioceras, similar to those here recorded, were seen" in place."

204

L. F. SPATH,

Quenstedt, occur with Xipheroceras and Asteroceras in Gloucestershire and will be referred to below as Epophioceras gen. nov. (fam. Arietidre s.s.).* The Coroniceras of the rotiforme zone are connected with Metophioceras by such forms as M. ccesar (Reynes). Coroniceras schloenbachi (Reynes) characterises the lower beds. The specific name was (doubtfully) used for a homreomorphous Epammonites of the isis group from Skye (Spath, 1922, p. 174). but Dr. Fiege's interpretation is now adopted. Coroniceras of the rotiforme-rotator type occur higher, as in Wurtemberg, but are mostly crushed impressions, and a doubtful example of the coronaries-group was found in bed 36 above, associated with what may be Arnioceratoides, i.e., reduced forms of the coronaries stock. The example figured by Reynes (pI. 9, figs. II-12) may be renamed Arnioceratoides spurius n. nov., but his fig. 10 of pI. 9, copied from Quenstedt (Jura, pI. 7, fig. 6) is the typical Arnioceratoides falcaries, differing but slightly from the tuberculate A. kridion (Rehl) Zieten sp. Ammon. falcaries (pars) of Quenstedt's later work (Amm. des Schwab. Jura, pI. 13, fig. 12) is an Arnioceras of the acuticarinatum group, and Ar. falcaries (Quenstedt) Schmidt (loc. cit., 1915, pI. 6, fig. 5, B.M. No. C25237) another species of Arnioceras (geometricusceratitoides group) for which the new name A. hercynicum n.n. may be proposed. The genus Paracoroniceras is represented by crushed examples. of P. aff. gmuendense (Oppel) and P. aff. crOSSl (Wright) from the base of bed 48, Ammonites S.s. (genolectotype : Amm. bisulcatus (Bruguiere) d'Orbigny) by one badly preserved fragment from bed 49 and a number of loose examples. These include various species of the bisulcatus-multicostatus type and allied forms like Amm. lyra (Ryatt)t wrongly identified by its author with Wright's" Arietitites bisulcatus " of plates 3 and 4. EpammrJ'nites of the latisulcatus-grecoi type have also been seen only in loose examples (B.M. No. C6195 and Miss Wood's ColI.). It is worthy of note that no Eucoroniceras, associated with Epammonites, e.g., in the top clays at Stockton, or Megarietites (development of the multicostatus group of Ammonites s.s.) have yet been found at Lyme. Fiege considered Amm. latisulcatus Quenstedt to be a large Vermiceras (of spiratissimum type) and Arietites latisulcatus Schmidt, the genotype of Epammonites, to represent the inner whorls of Ar. bucklandi. Ris interpretation of the latter, however, is based on the example • Genotype: Amm. land, oli (el'Orbigny) Pro 'rome, No. 33, p. 213 (Annal" Pal., vol. ii., '907. p. 2', pl. vii., figs. 4-5). Reynos's form (pI. "mi., figs. 1-3) with three distinct ~eels may be separated as Ep. rl'OIllClc.ilt1llll sp. nov. and Dumortier's example (vol. ii., 1867, pI. xxiii., figs. 1-2) with very oblique cost", and sharper keel, may be renamed Ep. ouinlinm
shore, Woreestenhire).

THE .U!MOt\ITES OF THE BLUE LIAS.

2°5

-figured by Wright in pI. I, and misidentified with Amm. bucklandi Sowerby, as typical of which may be accepted Mr. Tutcher's Keynsham specimen, figured in "Type Ammonites" (1919, pI. 131). Wright stated that the finest specimens of" Arietites bucklandi" he obtained were found on the coast near Lyme Regis, but though there occur in loose blocks numerous examples 9f Coroniceras of the bucklandi-solarium-pingue group as well as more or less homceomorphous forms of other genera, e.g., Epammonites, the exact bed of the true Coroniceras bucklandi is not yet known. A fragment of a depressed form, with less rounded whorl-section than the Coroniceras of the group just referred to, and possibly representing the outer whorl of a species of the group of Epammonites costosus (Quenstedt), has a whorl-height of 60 mm. and a thickness of 70 mm. and certainly comes from the charmassei beds, probably some distance below" Glass Bottle." But another p}Titised " bucklandi" seen on top of a fallen mass of "Glass Bottle" (bed 47) had at a diameter of 445 mm. a whorl thickness of 150 mm., with twenty-seven untuberculated ribs and rounded whorl-section. Since Dr. Fiege noticed that Coroniceras pingue (Quenstedt) also has a fairly wide vertical range, the use of the term "bucklandi" zone in a restricted sensc had perhaps best be avoided. Wright's (1878, pI. I, fig. I, BM. No. C25133) Lincolnshire example is drawn as too compressed, being somewhat worn, and its dimensions are at a diameter of 135 mm. : .29 - .32.52 and at 240 mm. : .28 - .30 - .52. It may be renamed Epammonites scunthorpense n. nov. Schmidt's (1915, pI. I, fig. 2) Harzburg "Arietites bucklandi," to judge by some of his material lately acquired in exchange by the British Museum, include similar forms, e.g., Epammonites macer and E. costosus (Quenstedt).* His Arietites bucklandi var. nodosus is probably allied to that punctate species of Epammonites that was previously referred to under Coroniceras schla:nbachi (see above, p. 204). Epammonites latisulcatus (Schmidt, non Quenstedt) according to Stockton and Lyme examples, has great resemblance to the true Arnioceras.

VI.

FAMILY ARNIOCERATIDJE nov.

In view of the close affinity of the true A rnioceras to Epammonites, from which they are perhaps partly derived, it may by some be considered unnecessary to separate the present family from some Ammonitidre. But the family Agassiceratidre, discussed below, similarly includes a few allied developments of Ammonitidre, separated merely for convenience, and it will be advisable to restrict Arietidm 5.S. to yet another assemblage, originating • Reynes's (1879), pl. xxi., fig~. 5-6, i!' only slightly more d€'prf's~t'd than QUf'nstedt'~ pJ. X" f.l.

206

L. F. SPATH,

in Arnioceratidre,* and including Arietites s.s. (turneri-brooki group) in addition to Epophioceras already discussed, Asteroceras, Hyftasteroceras, and Eparietites gen. nov. (created for the group of Amm. collenotii d'Orbigny, genotype to be Arietites tenellus Simpson, sp. in S. S. Buckman, 1912, vol. i., pI. 54). Hyatt's family, Oxynotidre, finally, comprises the last "Arietids" of the top of the Sinemurian and Lower Pliensbachian. Paroxynoticeras (genolectotype: P. salisburgense (Hauer) Pia, 1914, pI. I, fig. 2£.) and Slatterites, on present evidence, seem referable to this family rather than to Arietidre s.s. As already mentioned Hyatt had taken Coroniceras to be the type-genus of his family Arietidre, but the genus Arietites was 'Subsequently restricted by Mr. Buckman to Ar. turneri. and it is thus advisable to use the family name Arietidre for the assemblage to which A rietites s.s. belongs. As regards Arnioceratidre, at present we can distinguish only the early geometricum-ceratitoides-arnouldi group, with its off-shoot, the acuticarinatum-nodulosum-miserabile branch, all characterised by thtlir comparatively simple and shallow lateral lobes with few but distinct indentations; also the later Eparnioceras, which is assumed similarly to start with costate forms and to end in the smooth Ep. flavum S. S. Buckman (1918a, p. 208). To these late Eparnioceras I have provisionally attached Cymbites (1923a, p. 77), since " Agassiceras," its presumed ancestor, develops large forms and the early striaries group is too distant in date. But only future collecting in suitable beds will settle the exact systematic position of Cymbites as of Eparnioceras. The numerous intermediate species of Arnioceras may also yet be found to belong to a number of different stocks, so that it seems advisable to keep the genera. here discussed in a separate family. The Arnioceras material from Lyme, unfortunately, is not sufficient for a successful revision oJ the genus. Forms of the group of Ar. geometricus (non Phillips) Oppel sp., as typical of which I take the example figured by Schloenbach (1865~ pI. 26, figs. 3a-c.) and of Ar. ceratitoides (Quenstedt, 1849), occur, with Ammonites S.S., and Paracoroniceras, in bed 48, and probably similar but poorly preserved Arnioceras already in bed 46. Ar. obliquecostatum (Zieten) and doubtful Ar. acuticarinatum (Simpson) have been found in bed 5'0, characterised by hundreds of crushed individuals of Ar. nodttlosum (J. Buckman). The latter form in similar numbers but larger exalPples is found also in bed 52. There it is associated with several allied species, like Ar. insoUtum Fucini, and the var. longispirata. of the same form, also other species like Ar. d. insigne Fucini and • An interesting AN.inCt1'aS fauna, with a new species of A,.it/itt'~,.and the last Poramwctf'as: with smooth O'ltl:'f whorls, has lately been found at horizon 7of. The- alC;'lOl to post-'timCl'ihorizons,may -be' inchtdptl in'an Arietan age.

THE AMMONITES OF THE BLUE LIAS.

z01

Ar. d. abjectum Fucini, Ar. dimorphum (Parona) and Ar. italicum Fucini, then Ar. d. acuticarinatum (Simpson), and Ar. miserabile (Quenstedt), the latter often associated with Anaptychus. The last two species occur together on the Yorkshire Coast, and are also associated in Gloucestershire. It seems probable that these smooth species are the final members of the first" wave" of Arnioceras; for Ar. pseudokridion of Table Ledge (bed 53) belongs to a different stock and has, perhaps, greater resemblarrce to th8 early Arnioceratoides. No forms with persistently smooth inner whorls have yet been found in the shales above bed 52 (Euagassiceras and Pararnioceras beds)·, but it may be mentioned that Eparnioceras flavum (S. S. Buckman), the smooth end form of the second (bodleyi-) "wave," again has its Anaptychus (Wright, 1879, pi. I, fig. 7). Until a recognisable suture line ofthe true Ammon. semicostatus Young and Bird, however, and better specimens of this species are available, it is impossible to identify with certainty even the Yorkshire examples, coming from different horizons. It may be added that Blake's (1876, p. 288) Arietites semicostatus, associated in the same block with what probably is a malformation of an acuticarinatus like A rnioceras (" Arietites pauli Dumortier "in Blake) belongs to a different species, and that his A riet. difforme (Emmrich) apparently is closer to Young and Bird's species. Blake's forms are also different from Wright's Ar. semicostatus (1878, pI. I, fig. 8), which may be taken as genolectotype of Eparnioceras. This is probably from the same hed as the Charmouth examples previously (Spath I923a, p. 71) recorded as associated with Xipheroceras.

VII.

FAMILY AGASSICERATIDJE nov.

The genus Agassiceras was previously (Spath, I923a, p. 72), taken to include the striaries-sa ,zeanus group, to avoid a nomenclature different from that employed by Mr. Buckman (1909, vol. I, p. ii). If nomenclatorial ruling, however, is to be observed, the genus Agassiceras probably cannot thus be used, and it will have to replace what is now (in this country) called £tomoceras. Hyatt '(1874) only mentioned three species of Agassiceras, namely A. l(Evigatum, striaries, and scipionianum. These were quoted again by Fischer (1879) who suggested " Agassiziceras" as a better name. Zittel (1885, p. 456) only mentioned two species, namely Ag. l(Evigatum and scipionianum, and Haug (1887), redefined the genus, still excluding the group of A. sauzeanus d'Orbigny. But Mr. Buckman in two papers (1894, p. 361, and 1898, p. 459) selected A. scipionianus as the type of Agassiceras. It is true' that Hyatt (1900, • The crusbed material recorded previously (Qua,t. l.tI.... G,ol. Soc., 1923, leble to p.84) w.s identified merely by tbe type of ribbing and tbe presence of "A,n,o,..,as nodulosu", " ;n paltlcuJar is doubtful.

208

L, F. SPATH,

p. 575) created the new genus lEtomoceras for A. sc£pionianus ; but Agassiceras was then included in Oxynotida:, together with Cymbites (in Zittel's 1921 edition (p. 557) it is still considered to be synonymous with Cymbites) and since A. scipionianlts has been selected as genotype of Agassiceras, it is impossible to redefine the genus and choose a different type. The necessary change of nomenclature is disturbing but may as well be affected now as a.t some future date. The Lyme species of this redefined Agassiceras include a number of crushed examples of A. colesi (J. Buckman) from the shaly beds 50 to 52. Paracoroniceras d. crossi (Wright) quoted above from bed 48 shews considerable resemblance to large Agassiceras scipionianmn (d'Orbigny) and Ag. scipion.is (Reynes) Hyatt, but the sub-tricarinate ventllr and absence of terminal tubercles on the ribs are characteristic. There appears to be no doubt that Agassiceras with the more or less parallel development Euagassiceras (suggested to replace Agassiceras as previously employed, genotype to be A 111m. sauzeamls d'Orbigny, Pal. FranQ. Ter. ]ttr., vol. I (1844), p. 304, pI. 95, figs. 4-5), and their off-shoot Pararnioceras Spath, form a well separable group of derivatives of the family Ammonitida: 5.5. The only forms of Euagass1:ceras occuring below Table Ledge are crushed examples of Eu. strl:aries, Ell. spinaries (Qllenstedt), and Ell, halecis (J. Buckman), evidently an assemblage similar to that recorded (Spath, 1923a, p. 84, table) from higher beds, but here characterised by the addition of abundant Arnioceras nodllloS1111t and Agassl:ceras calesi. Antmonites gaudryi, Reynes (1879, pI. ZZ, figs 4-6) is a form of Megarietites and the species previously (Spath, Igz3a, table p. 84), recorded (after Buckman) as " Agassiceras gaudryi " is a homceomorphous development of the group of Euagassiceras reynesi (Spath), hardly well enough preserved, however, to be given a new name. Similarly, "Agassiceras d. terqllemi" (Spath, 1923a, p. 72) may have nothing to do with Reynes' species (lectotype,1879, pI. 19, figs. la, II), which is rather too evolute for an Euagassiceras. On the other hand the present family includes Pararnioceras alcinoiforme nom. nov. (= Ar. rotiformis Wright, pI. 5, fig. 4, B.M. No. (1927) with a diameter of 8 (not 7) inches and a mode of preservation that does not suggest Blue Lias bf Lyme. Its resemblance to forms like Metophioceras casar (Reyncs) is great, but the suture-line is that of the Agassiceratids.

PROC. GEOL.

Assoc.,

VOL. XXXV.

PLATE

18.

c d X 5/

AMMONITES OF THE BLUE LIAS.

(For explanation see p. 209.) [To face

p. 208

THE

A~l;IIOXITES

OF THE BLUE LIAS.

2°9

EXPLANATION OF PLATE 18. I.

2.

3.

4.

Psi!ophyllites hagenowi (Dunker). Hettangian, hagenowi bcd. a. Lyme Regio, impression in shale (bed H. 67a). ColI. W. D. Lang. No. 5584. b. Holderness Drift (B.M. No. CI7873). See C. Thompson. Quart. JOUYIl. Ceo!. Soc., vol. lxix. (IgI3), p. 170. Suture-line represented in text-fig. 12a, b, p. Ig2. c. Example from Exten. nr. Rinteln, Hanover, with body-chamb·;r. Suture-line figd. text fig. 12, e. d. Sectional outline (x 5) of another Exten specimen, to show rounded shape of inner whorls. Sch!otheimia similis ~p. nov. Fragment from bed H gI, CQII. 'V. D. Lang. 5609, pars, to sh~w suture-hne. b. Sectional outline. TVaehneroceras iapetus sp. nov. a. SEfctional outline of inner whorls (X 4), and b. side view of earliest chambers (X 30) of a Barrow-on-Soar example (L.F.S. 8(3) showing one distinct constriction, and traces of others. Compare suture-line development of same example in textfigs. 13 b-f, p. Ig6. Arnioceras pseudokridioll sp. nov. a, b. Side views of two crushed examples (typical preservation) from Table Ledge (bed 53), L.F.S., Nos. 894-5. (See Quart. JOUYll. Ceo!. Soc., vol. lxxix., 1923. p. 71). LIST OF WORKS CITED.

BLAKE, ]. F.-1876. In TATE and BLAKE. Yorkshire Lias. BONARELLI, G.-1900. Ccfalopodi Sinemur. dell' Apennino Centro Pal. Ital .• vol. v., p. 55. BRAUNS, D.-I871. D~r Untere Jura. BUCKMAN, S. 5.-1894. Jurassic Ammonites. The GerlUs Cymbites. Ceol. Mag., p. 357. --18g8. Some Divisions of so-called Jurassic Time. Quart. Journ. Ceo!. Soc., vol. liv., p. 442. --1906. Some Lias Ammonites. Proc. Cotteswold Nal. Field Club, vol. xv.• p. 231. --1918a. Jurassic Chronology-I. Lias. Quart. J ourn. Ceol. Soc., vol. lxxili., p. 257. --1909-23. Yorkshire Type Ammonites, vol. i., Igog-12 ; vol. ii., 1913Ig. Type Ammonites, vol. iii., 1919-21, vol. iv.• 1922-3. CHAPUIS. F.-I858. Nouvelles Recherches s. I. Ter. Second d. Luxemb. 1. Mem. A cad. Roy., Belg., vol. xxxii., pI. iii .• fig. 4. CRICK. G. C.-Ig22. Notes on Specimens of Cephalopoda figured in Tate and Blake's Yorks. Lias. Naturalist, Nos. 787-8. DIETZ, A.-Ig23. Untersuchungen ii. d. Lobenlinien d. Ammoniten des Lias rx--y. N. jb. f. Min. eYe. Beil. Bd. xlvii. DUBAR. G.-1923. Note sur I'Hettangien et Ie Sinemurien a I' W. de Mezieres. Ann. Soc. Geol. Nord., vol. xlviii .• 2. DUNKER. W.-1847. Ub. die im Lias bei Halberstadt vorkomm. Verstein. Pala!Ontogr., vol. i., p. 115. pI. xiii., fig. 22. EpSTEIN. L.-1908. Psiloceras Baltzeri, n. sp. aus den Angulaten-Kalken von Vaihingen. jahresh. Ver. Vaterl. Naturk. Wurttemb., vol. lxiv., p. 420, text fig. FIEGE. K.-1923. Biostratigraphie der Arietenschichten Nordwestdeutschlands und Wiirttembergs. Inaug. Dissert. Giittingen. FISCHER. P.-187g. Subdivisions des Ammonites. journ. Concho/. Paris, July 1879. p. 3 6 .

2IEl

L. F. SPATH,

FREBOLD, H.-I922. Phylogenie und Biostratigraphie d. Amaltheen~ etc. XV. Jahresb. Niedersachs. Nat. Ver. (Ceol. Abt.), p. IS. --1923. Abspaltungen von Lytoceras im Unto und Mittl. Lias. Mitteil. Mus. Essen, Heft 2, p. I. FUCINI, A.-I9II. Alcune interessanti Ammoniti di Pioraco. Rill. ltal. Paleont., vol. xvii., fasc. 3, p. 4S. HAUG, E.-I887. Uber Polymorphidae. N. J.b. I. Min. etc., vol. ii., p. 94· --1907. Traite de G~olog:e, vol. ii., fasc 2. HOLLAND, F.-IgDO. UOOr Alpine Formenreihen von Psiloceras aus. Schwaben, Jahresh. Ver. Vaterl. Naturk. Wurttemb. vol. Ivi. (I899)~ p. 498. HYATT, A.-I867. Fossil Cephalop. Mus. Camp. Zool. Bull NO.5. --1874. Two New Genera of Ammonites, etc., Proc. Boston Soc. Nat. Hist., vol. xvii., pp. 226-8. --1889. Genesis of the Arietidre. Smithsonian Contn'butions to Know-· ledge, No. 673. --1900. Cephalopoda, in Zittel's Text-Book of Palreontology (Transl. Eastman), vol. i. JOLY, H.-IgD8. Jurassique Infer. etMoyen de la Bard. N.E. du Bassin. de Paris. KILIAN, W., and BLANCHET.-I923. Ammonites recueillies par Ie "Poltl"quai-Pas ?" C. R. Acad. Sci. Paris, vol. clxxvi., p. IS6. LANG, W. D.-I924. The Blue Lias of the DeYQJl and Dorset Coasts. Proc. Ceol. Assoc., vol. xxxv., p. 169. LANGE, W.-I922. Uber den Untersten Lias der Herforder Mulde. JaMb. Preuss. Ceol. Landesanst. vol. xlii., Heft I., 1921. LEMOINE, P.-I9II. Geologie du Bassin de Paris, p. 79. MEEK, F. B.-I 876. Invertebr. Cret. Foss. Missourie, in Hayden, Geol. Surv. Territ. U.S. Ceol. Surv., vol. ix., pp. 44S-6. ORBIGNY, A. D'.-I842-SJ. Paleontol. FranQaise, Ter. Jurass. vol i. --I8So. Prodrome. I., Ter. Jurass. vii. PIA, J. VON.-I9I4. Untersuchungen ii. d. Cattung Oxynoticeras. A Mand. K. K. Ceol. Reichsanst., vol. xxiii. POMPECKJ, J. F.-I893. Beitrage z. Revision der Ammoniten d. Schwab. Jura. Jahresh. Ver. Vaterl. Naturk. Wlirttemb., vol. xlix. QUENSTEDT, F. A.-I 883-8S. Ammoniten des Schwabischen Jura. I. Der Schwarze Jura. REYNES, A.-J879. Monographie des Ammonites. RICHARDSON, L.-JgD8. Section of Lower Lias at Hock Cliff. Proc. Cott,swold Nat. Field Club, vol. xvi., p. 135. RoTHPLETZ, A.-I888. Karwendelgebirge. Zeitschr. Deutsch-Oste". Alpen Ver., vol. xix., p. 428. SALFELD, H.-I9I9. AnsgestaItung der Lobenlinie bei Jura-und KreideAmmoniten. Nachr. K. Ces. Wiss. ClJttingen, Math. Naturw. KI. --1923. Die Bedeutung der Konservativstamme f.d. Stammesentwicklung d. Ammonoideen, Leipzig, 1923. SCHLOENBACH, U.-I86S. Beitr. Z. Palreont. d. Jura- und Kreideform. Palmontogf', vol. xiii., p. 8, pI. xxvi., figs. 2a-c. SCHMIDT, E. W.-I9I4. Die Arieten des UnterenLias von Harzburg. Beitr z. Pal. & Strat. d. N.W. Deutschen Jura, iii., Palaeontogr, vol. lxi., p. J.

THE AMMONITES OF THE BLUE LIAS.

2II

SoWERBY, J. and J. DE C.-18I2-46. Mineral Conchology of Great Britain. vols. i.-vii. SPATH, L. F.-1914. The Development of Tragophylloceras Loscombi. Quart. Journ. Ceol. Soc., vol. lxx., p. 336. --19 15. On Schlotheimia Creenoughi, J. Sowerby sp. Ceol. Mag., p. 97. --1919. Notes on Ammonites. Ceol. Mag. p. 27. --1922. Lower Lias Ammonites from Skye. Ceol. Mag.. vol. lix., pp. 170-76. --1923a. The Ammonites of the Shales-with-Beef. Quart. Joun•• Ceol. Soc., vol. lxxix., pp. 66-88. --1923b. On Ammonites from New Zealand. Ibid. pp. 286-312. --1923c. Monograph of the Ammonoidea of the Gault. Pt. I., Mon. Pal. Soc., vol. for 1921. TERQUEM, O. and Piette, E.-1865. Lias Superieur de l'Est de la France. Mem. Soc. Ciol. France (2) vol. viii., p. 29, pl. I, figs 3-5 (suture-line diagrammatic) . THOMPSON, C.-1913. Derived Cephalopoda of the Holderness Drift. Quart. Journ. Ceol. Soc., vol. lxix., p. 169. TRUEMAN. A. E.-1922. Liassic Rocks of Glamorgan. Proc. Ceol. Assoc., vol. xxxiii., p. 281, pI. 9. fig. A. TUTCHER, J. W.-1918. In S. S. Buckman. Jurassic Chronology-I., Lias. Quart. Journ. Ceol. Soc., vol. Ixxiii., p. 278. --1923. Lias about Keynsham. Proc. Bristol Nat. Soc. (4), vol. V. (1922). WAEHNER, F.-1882-1898. B~itrage zur Kenntnis der Tieferen Zonen Beitr. des Unteren Lias in den Nordostlichen Alpen, pts. I.-VIII. Pal.&> Ceol. Osten'. Ung., vols. ii. to xi. --1886b. Zur h"lteropischen Differenzierung des Alpinen Lias. Verh. K. K. Ceol. Reichsanst., NO.7. WOODWARD, H. B. 1893. Jurassic Rocks of Britain, III. Lia5 of England and Wales (Mem. Ceol. Surv.). WRIGHT, T. 1878-86. Monograph Lias Ammonites. Mon. Pal. Soc. ZIETEN, C. H. DE. 1830. Petrifications de Wurtemberg, p. 3, pI. iii., figs. la, b. ZITTEL, K. A. 1881-85. Handbuch der Palreontologie. Abt. I. vol. ii.: Mollusca und Arthropoda. --1921. Grundziige der Palreontologie. 5th German edition (F. Broili), Abt. I. Invertebr.