A preliminary account of the British Fossil Voles and Lemmings; with some remarks on the pleistocene climate and geography

A PRELIMINARY ACCOUNT OF THE BRITISH FOSSIL VOLES AND LEMMINGS; WITH SOME REMARKS ON THE PLEISTOCENE CLIMATE AND GEOGRAPHY. By MARTIN A. C. HINTON. (Read],,,,e Srd, /9/0.)

T

H E monograph on the British Fossil Voles and Lemmings is now, after several years of labour, nearing completion, but some considerable time will yet elapse before it can be published. As some of the results of this research are of general interest and have a not unimportant bearing upon certain geological speculations, as well as upon certain questions of geographical distribution, it may be useful to publish the following preliminary account of them and the conclusions to which they are leading, reserving, of course, the full treatment and description of the species dealt with for the text and illustrations of the monograph. Moreover to people who have material at their disposal which I have not hitherto seen this communication may serve as an invitation to inform me of its existence, and so enable me to make the work more complete than it is at present. At the moment I have to thank my friends Mr. W. J. Lewis Abbott, Dr. Frank Corner, Mr. A. S. Kennard, Dr. H. C. Male, the Reverend E. H. Mullins, Professor S. H. Reynolds, Mr. A. C. Savin, Dr. R. F. Scharff and Mr. G. White for the loan of much valuable material, and Mr. H. A. Allen, Dr. C. W. Andrews, Major Barrett-Hamilton, Dr. F. L. Kitchen, Mr. E. T. Newton, Dr. Forsyth Major, Mr. Gerrit S. Miller, Mr. Oldfield Thomas, and Dr. A. Smith Woodward for much courtesy and valuable assistance The British fossil voles and lemmings belong to the following genera :-Mimolll)'s, Euotomys, Arvicola, Pitymys, J1.ficrotus, Lemmus, and Dicrostonyx. Of these, one, Mimo1Jl)'s, is totally extinct; whilst three, Pitymys, Lemmus and Dicrostanyx, are extinct in Britain, though living elsewhere. During Tertiary times certain mouse-like rodents appear to have branched off from the more generalised Muridre in order to pursue an evolutionary path different from that followed by the main body of the Mice and Hamsters. In gradually adopting a more earth-bound, and in some cases even a subterranean mode of living, and in accommodating themselves to tougher and coarser foods, these deviating forms were subjected to a process of specialisation which had for its result the production PROC. GEOL. Assoc., VOL. XXI, PART 10, I9IO.J 36

MARTIN A. C. HINTON ON

of the great group of Microtine Rodentia. Outwardly this specialisation manifests itself principally in the shortening of the external ear and tail and the decrease in the size of the eyes, whilst internally the skeleton and dentition have undergone great modifications. Thus the sympll)'sis pubis is greatly shortened and the skull, under the influence of the increasing strength of the masticatory muscles and hypsodont teeth, becomes quite massive, several of its bones fusing at a very early age. * The molar teeth, low-crowned, tubercular and rooted, grinding or crushing teeth in primitive murines, now become high-crowned prismatic structures, adapted for shearing and slicing rather than lor grinding, developing roots, in more generalised voles, only in the adult stages, or else remaining rootless, the teeth growing persistently from permanent pulps. But even in the most highly specialised voles and lemmings we find in the young unworn molars a sort of living memorial of the pedigree, since such teeth show an ephemeral tubercular enamel cap above the prismatic body of the tooth. For reasons to be dealt with elsewhere, the anterior cheektooth, above and below, in the voles and lemmings is regarded as a persistent milk-molar, the dental formula for the group being written consequently as ; It dm.! m-i~ = t x 2=16. Throughout the group we meet with evidence that complex as the anterior cheek teeth are in many cases, they have nevertheless been derived from still more complex forms, and that the progress of the molars from a brachyodont and rooted condition to a hypsodont and persistently growing one has been correlated with a reduction of parts and consequent simplification of structure, the simplification varying much in amount in the various genera and individual species. In the later Pliocene deposits of Britain we meet with the remains of species belonging to four genera, viz., ilfilllo11l)'s and Evotolll)'s with rooted, and Pit)'lll)'s and 1I1icrotus with rootless molars. I do not purpose to discuss the questions relating to these Pliocene voles here at any length; it will almost suffice to say that I entirely agree with Dr. Forsyth Major t that not one of the numerous species represented by the fragmentary remains before us can be referred to a living form. With regard to the species of ilficrotus it may be stated that in the younger teeth from the Cromer "Forest Bed" series ephemeral complications are met with of a far more extensive kind than any as yet observed in the young dentitions of recent forms. The species of lIfilllonl)'s, when traced from the Norwich Crag * Winge Vidensk. Meddel. Naturhist, Forewing, 1881, pp. 21"4-6. "Jordfnndne og

Nulev-nde Gnavere." E. Mwseo Lrundi, 18tl7, p. 123j 'v Gronlands Pattedyr,' Meddel. om. Grontana, x xi , p. 358. Forsyth Major, Proc, Zool. Soc., ]9:)2, vel, i , p, 1°7, and Geological Magazine) dec. v, vot. v, P. 329.

+

THE BRITISH FOSSIL VOLES AND LEMMINGS.

491

to the Upper Freshwater Bed of West Runton, as noted already by Forsyth Major," and, I can now add, to the High Terrace Drift (Pleistocene) of the Thames Valley, present us with a series of stages marking the progression of the molars towards hypsodonty and persistent growth, and these stages may be used for zonal purposes. The following is a synopsis of the species now recognised by me, but there are other forms which, with the materials at present available, cannot be satisfactorily defined : a. ;\10LAR ROOTS DEVELOPED EARLY. 1.

Mi1Jlom)'s neu toni, Forsyth Major.']

2 Jrfimo1Jll's plioramieus, Forsyth Major.j 3. J1imomvs reidi. n. sp.§ Dm. T highly specialised as regards reduction of third outer valley; but generalised II it h respect to persistently confluent dentinal spaces. Size small,

Norwich Crag to Lower Freshwater Bed (Cromeria n). Norwich Crag. Weybourne Crag.

b. MOLAR ROOTS DEYELOPED LATE.

4. Mimomvs sauini, n , sp.11 The" prism-fold" of yd outer prism in dm, T is persistent.

Upper Fresh watel' merian).

Bed

(Cro-

5. illimo'/I)'s maiori, n. sp.'

Upper Freshwater rnerian),

Bed

(Cro-

Upper Freshwater merian ),

Bed

(Cro-

Dm. T with 3rd outer valley unreduced. 6. ,AfimomJ's inrermedius, Newton.** Om. 'T reduced so as to closely resemble corresponding tooth of Aruico!a.

7. Mimomys cantianus,

n, sp·tt

Molar roots developed very late in life.

High Terrace Drift of Tbames Valley (Pleistocene.)

PLEISTOCENE. HIGH TERRACE DRIFT.

The earliest Pleistocene deposit in Britain known to yield remains of a microtine fauna is the High Terrace Drift of the Thames Valley. The fossils in question were obtained from a * Forsyth Major, Proc. Zoo!. Soc.,

1902, vol, I, P. 107. 1- Op, cit., p. 103. Text fig. 13, fig. 7; text fig. 14J fig. 10. ~ Op . cit., p. ro j. Text ~g. 13, figs. 2, 5, 8, g. ~ Newton, Vertebrata oj Forest Bed, PI. XIII, fig. 8, locality erroneously given in -explanation of Plate as H Upper Freshwater Bed, West Runton.' This specimen comes from Weybourne Crag, Trimingham. II Forsyth Major, Proc, Zool. Soc., 1902, vol. i, p. 106. text fig. 15, fig. 22. ,. ap. cit., p. 106, text fig. IS. fig. 26. "" Newton, Vertebrata of Forest Bed. PI. XIII. fig. 3. H Hinton and White, Proc, Geol; Assoc., vol, xvii, p. 4'4.

49 2

MARTIN A. C. HINTON ON

small gravel-pit near Greenhithe, in Kent, discovered by the late H. C. Stopes. * Several teeth of iJ;fimomys canrianus were found together with a good many specimens referable to a small species of Evotonzys. A single second upper molar (m. I) was obtained presenting three internal angles, referable either to a Pitymys or to a tetramerodont species of Microtus. Other rodents known from this deposit are a species of .lv/us, allied to .lI:f. sylvaticus, and a species of Trogontheriulll.·r These Rodentia form part of a most interesting mammalian fauna possessing many points of similarity with that of late Pliocene times. I have determined the following species: Elephas antiqeus" Rlli1loceros megarhinlts ,three species of Ceruus, one of them having affinities with C. broumi and the Fallow Deer; Equ1!s sp., approaching the Pliocene E. stenonis r Bos sp. ; Sus sp., a form with a very primitive foot skeleton; Canis, a species agreeing in size with a mediumsized dog, but having the ulna comparatively unreduced; Felis leo or similar large form; and Delphinus sp. Excepting the elephant, rhinoceros, Felis and possibly two of the deer, all the forms mentioned differ from those whose remains are found in the earliest deposits of the next or Middle Terrace of the Thames Valley at Grays, and they approach those occurring in the " Forest Bed" series and the Upper Vald'Arno Pliocene.

MIDDLE TERR.\CE DRIFT.

Although the deposits of the Middle Terrace of the Thames Valley, taken collectively, form one stage in the physical history of the valley, an attentive study of the paleeontology reveals the fact that the deposits of this horizon are not all of the same actual age, but that on the contrary they represent an enormous period of time during which vast changes in the mammalian inhabitants of south-eastern England were brought about. a. Grays Thurrock.-One of the earliest Middle Terrace deposits is undoubtedly the famous brick-earth of Grays Thurrock, and from this an abundant microtine fauna has been gathered.] The result of my study of the Grays fossils is that I am now unable to refer any of the voles from this locality to recent species. The forms represented are: Arvicola sp., a small species distinct from any living member of the genus, and which also occurs at Ilford ; Evotonzys sp.; a species of Microtus, apparently allied to Ai. nivaloides, Forsyth Major§; another one presenting some similarity to M. anglicus, Hinton, a form characteristic of a much later horizon; and an early member of the M. agrestis group, *

t t xvii, §

Stopes.]ourn. Anthroo, Inst., vol. xix, p. 302. and reprint 190r~ Newton, Geol, Mag., dec. iv, vol. ix, P. 385, 1902. Hinton and Kennard, Essex Naturalist, vol. Xi. p. 347, 19Qo; Proc. Geol. Assoc.. vel, p. 142.

Hinton, Proc, Geol. Assoc., vol. xx, p. 45, PI. I, Fig. 5.

THE BRITISH FOSSIL VOLES AND LEMMINGS.

493

characterised chiefly by the constant development of a fourth outer angle in the last upper molar (M. agrestoides, sp. n.) These forms are for the most part known only from Grays, though some of them may occur in the slightly later brick-earth of Ilford. With regard to the other mammalia from Grays the leading features of the assemblage are the presence of an Ape, lI1acams, which is now known to occur also in the Forest Bed ':'.: the abundance of remains of Elephas antiquus and Rhinoceros megarhinus " the presence of species of Sus and Hippopotamus; and the complete absence of what are generally regarded as northern forms, such as Rlzilloceros antiquitatis and Ovibos. Unfortunately, little is known of the Rodentia in the somewhat later deposit at Ilford beyond that, in addition to the ubiquitous Beaver, remains of a small species of Arvicola and some remains of lI£icrotus, insufficient for specific determination, have been found. The other mammals show a distinct advance upon those of Grays; thus Rhinoceros hemitO!chus replaces Rh. megarhinus to a large extent, and a small form of Elephas primigenius becomes abundant, whilst E. antiquus is now rare. There is, however, still no trace of the" northern mammalia," t and a comparison of the species lists shows that the Ilford deposit agrees much better with that of Grays than it does with the brickearth of Crayford and Erith. t b. Crayford and Erith.-The brick-earth of Crayford and Erith is the latest of the Thames Middle Terrace deposits from which a microtine fauna is known. Not a single one of the voles occurring in the Grays deposits has been found here, notwithstanding the fact that microtine fossils are very abundant in, and have been extensively collected from, the deposit; their place is taken by a series of new comers. The species represented are :--

Microtlls ratticeps, Keys. and BIas. M. (ChioJlomys) niuaiis, Martins. Microtlts sp. (approaching liE. allglims, Hinton). Lemmus, sp. Dicrostonyx gulielmi, Sanford. Other rodents occurring are Castor and SperlllojJhilus, the latter genus appearing here for the first time in the English Pleistocene.§ Rhinoceros tl1zliquilalis is the common rhinoceros, * Hinton, Geol, Mag., dec. 5, vol. v, p. 440, PI. XXIII, Figs. 1-3, 1908. A very few specimens referable to Rhinoceros antiquiiatis have been found at Ilford , This deposit probably dates the arrival of this species in south-eastern England. Davi~s, Cat. Brady Coti., p. 37; Dawkins, Nat. H ist, Reu., 1863, p. 534; Hinton, Essex N aturatist, -vol. xlt. p. 235 (1902). t Davies, Cat. Brad. Colt., p. 62; Whitaker, "Geology of London," vol. I, p. 336 (J889) ; Hinton and Kennard, Essex Naturalist, vol, xi, p. 346. § Remains of Spermoptiitus have been found in the" Arctic Freshwater Bed I, at Mundesley, vide Newton, Geol. lJJag., dec. 2, vol. Iv, p. 51 (1882), and Reid, "Pliocene Deposits of Britain" (r890), p. 197. I am not at all sure of the true position of this deposit in the Pleistocene series; it may be much later than is usually supposed; in

+

any case the Crayford deposit gives us the date of the arrival of the late Pleistocene Sperniophilus in this country.

494

MARTIN A. C. HINTON ON

the other two species having now become excessively rare. Remains of Elep/ws pril!ll;l{enius-the normal form-abound, and those of OZ't"lJ(IS have been met with. The Crayford deposit thus marks the time when the "northern" mammalia began to arrive in south-eastern England in force and to replace the older "southern" types. CLEVEDON CAVI'.

The deposit filling the Clevedon Cave appears to be of about the same age as the Crayford brick-earth, * or possibly a trifle older, since no lemming remains have been found in it. Three species of A:ficrotus occur, viz. : Jl:fi(riltus ratticers, Keys. and BIas. hJ. (C/tiollomys) lIivalis, Martins, A£. male':, Hinton. In my description of A£. maled I regarded the species as a member of the AI. 1tivalis group, but now, having restudied it with further material, I do not think it has any special affinity with hI. nivalis, but that it is a species with (typical!y) a rather generalised dental pattern such as that which probably characterised the ancestor of several species like hI. ratticeps and il:f. nivalis ; the teeth figured by me in fact only represent the nivaloid variation of A£. ma/c]. ICHTHAM FISSURES.

One of the latest and best known Pleistocene deposits in this country is that of the Ightham Fissures, whence a great many mammalian remains have been obtained.] Whether my view, that some of the Crayford and Clevedon voles are members of the M lIivalis group,§ be right or wrong, there cannot be the least doubt that the forms in question had become entirely extinct in this region at the time of the filling of the Ightham Fissures. The following is the list of microtime known from Ightham: Evotomys, two species. Armco/a abbotti, Hinton.fl Microtlls agrestis ncp,lectlls A£. arua/is, Pall. M. corneri, Hinton.] A£. allglicus, Hinton. ':'* M ratticeps, Keys. and BIas Lemmns lem11llts. Dicrostonyx hense/i, Hinton. tt Of the two species of Euotomys occurring at Ightham the one differs from Evotomys /iercynicus, the form inhabiting south-eastern England, in its larger size and heavier molars, and agrees with the * Reynolds, Bristol Nat. Soc. Proc., vol. i, P. 183; Hinton, ibid., p. 190. t Hinton, Proc, Geol. Assoc., vol. xx, p. 4-8, Pl. I, Figs. 23-27. :t: Abbott, Qual't.]ouyn. Geot. Soc., vel. 1, p. 171; Newton, ibid., p. 188 ; op. cit"! vol, Iv, p. 42I. § Hinton. Prac. Geol. Assor .• vr l. x x , p. 45. 11 kl lnton, AwL.. and lYlag. Nat. Hist., series 8, vol. vi (I9LO), p. 35. 'IT ap. cit., p. 34· ** Op, cit., p. 36. Hap. cit., p. 37.

THE BRITISH FOSSIL VOLES AND LEMMINGS.

495

voles of the E. nageri group, members of which now live in the Channel Islands, Skomer Island, and the Alps." The other is a smaller form with very small teeth, making perhaps a near approach to the E. ruti/us of Northern Europe. The fossil water-vole (Arz!icnla alJbotti) is a most interesting and important species. Its skull is highly specialised for a subterranean or fossorial mode of living, as is evidenced principally by the forward inclination or flattening of the occiput and the straightened and protruding incisors. In the Alps and other parts of central Europe water-voles are found living which have forsaken the water, and one of them, A ruicola sdierman (Alps and South Germany) has quite mole-like habits. In this living form the skull is modified in a way similar to that seen in A. abbotti, but the specialisation is not so extreme -r The form of lVI. agrestis occurring at Ightham is not M agr. hirtus, the living representative of the group in S.E. England, but a form like that known to exist in the highlands of Scotland, 11£. agr. negleetus. The Ightham 111. arvalis is apparently identical with the Belgian form, whilst the 11£. rattieeps remains agree closely with the form living in Holland and North Germany. One of the most in teresting voles from Ightham is 31. corneri, a member of the aruaiis group, with a large and robust skull presenting peculiarities which force us to regard it, without any doubt, as the immediate ancestor of the remarkable forms now living in the Orkney Islands.j Another member of the group, M sarnius, has lately been discovered in the Channel Islandss and a comparison of this form on the one hand, and 111. orcadensis and its allies on the other, has shown that the geographically intermediate M corneri is also anatomically intermediate between these living forms. II The fine skull material before me proves that the species so long referred to M "~regalis" by palreontologists, although a member of Kastchenko's "Stenocranius" group, cannot possibly be identified with M gregaiis, Pallas. All the living members of the "Stenocranius" group are Asiatic species, and therefore, in order to call attention to the western habitat of the fossil form, I have named it 11£ anglicus.~ The" Stenocranius " group represents simply a terminal phase in the evolution of the skull and dentition in the M. arvalis group, and I think the most likely explanation of lI£. anglieus is that one of the species of the arualis group in Pleistocene Europe happened to strike into and * Barrett Hamilton, Proc, Rov. Irish A cad., XXIV, Sec-t. B, P.31.5 (1903) j Miller, Ann. and Mal;. Nat. Hist., series 8, vol. i, P. 19~; Proc, H'ash. Acad. Sci., vol. xi, p. 94 ('9 0 0 ) . + Miller, Proc. Bioi, Soc. Wash. (1910, March), p. 21; Hinton, Ann. and Mag. Nat. Hist., series 8, vol. vi, p. 34 (1.910). :t: Millais, Zoologist, 19°4-, p. 241, H Brtttsh Mammals." vol. ii, p. '278, PI. 234, Fig. '2 ; Clark and Bradley, Ann. Scott. Nat. Hist., 1905, p. I; Forsyth Major, Ann. and st ag, Nat. Hist., series 7, vol. xv, p. 324. . § Miller, Ann. and Mag. Nat. Hist., series 8, vol. iii, p. 410. 11 Hinton, Ann. and Mag. Nat. ll ist., series B, vol. vi, p. 35. '"T 0,'. c t., P 36.

MARTIN A. C. HINTON ON

proceed as far along the same path of evolution as many of its Asiatic brethren have done. With the advantage of really excellent material I have been able to show lately that a suggestion, made so long ago as 1872 by Dr. Forsyth Major,* that two species of Dicrostonyx lived in Europe during the Pleistocene period, is in fact right, and, further, that both the forms in question are extinct t One of these species, D. henseli, Hinton, a small form with the dentition reduced as in the much larger D. hudson ius of Labrador, occurs at Ightham and elsewhere, in the Langwith Cave, Derbyshire, the Doneraile Caves, county Cork, and the diluvium of Quedlinberg, in Saxony.'] The second species, for which I have to use Sanford's name D. glilielmi,§ is much larger than D. lZfIlselz; and in its more complex molars agrees with D. torquatus, Pallas, from Greenland. It is known to occur in the Somerset Caves.] the Wye Cave.fl the Langwith Cave,** the Crayford and Erith brick- earth, probably in the Edell' ": Cave in county Cork, and at Neschers,tt Puy-deDome (Auvergne). With regard to the species of Lemmus, that which occurs at Ightham I am unable to distinguish from the ordinary Scandinavian lemming. but Dr. Male has lent me some specimens from the Uphill Cave, near Weston-super-Mare, 'which, although fragmentary, are probably to be referred to another species. Besides the ten microtine species above mentioned, remains of Mus s)'lvaticus, both large and small form, t t Spermophilus,§§ Ochotona (= Lagomys) I1I1 and Lepus zlariabilis anglims ~~ have been found at Ightham. Among the larger mammals the most noticeable new comers are the Reindeer and the Arctic Fox.*** The succession of microtine faunas which we have just traced is of great importance, since it can be used for purposes of classification, and we are enabled with its aid to correlate the various cave deposits, with each other and with the drifts, with some measure of certainty. The classification suggested is shown in the following table; the first few species named in each horizon are the most important ones for zonal purposes; whilst the names of the more significant non-microtine rodents are added. * Forsyth, Major. Atti di Soc. Ital. di Sci. Nat., vol. xv, p. 125 (1872).

+

Hinton, Ann. and Mag. Nat. Hist., series 8, vol. vi, p. 37. t Hensel, Zeits. d. Deutsch Geo!. Ges.. Bd. vii, P. 493 (1855). I am greatly indebted to Dr. Scharff for the loan of the Irish material. § Sanford, Quart. Journ. Geol. Soc., vel. xxvi, p. 125, PI. VIII, Fig. 4(1870). II O», cit., p. '25. ~ Dorothy Bate, Gear. Mar., dec. 8, vol. iv, p. '04, Fig. 3. ** Hinton, Ann. an d Mug, Nat. Hist., series 8, vol. vi, p. 38 (IgIO). tt Op, cit .• p. 38. Newton. Quart. [ourn; Geol S(1C, vol. 1, p. 194; ibid., vol. lv, p. 424; Proc. Zool. Soc., r899, p. 77. Iv/us tewisi is, I think, identical With the large form of M. sylvaticus= M. sylo, wintoni and fiavicollis. ~~ Newton, Quart. jOttJ11. Geol. Soc., vol. lv, p. 422. 1111 Newton, ibid" vol. I, p, 194:r~ Hinton, Sci. Proc, Roy. Dublin Soc., vol. xii, new series, p. 225 (1909). :,** Newton, Quart. [ourn; Gecl, Soc., vol. 1, p. 202; Reynolds, ~~ British Fossil Canldae," Mem, Pal. SDC., '9°9.

a

THE BRITISH FOSSIL VOLES AND LEMMINGS.

497

TABLE SHOWING GEOLOGICAL DISTRIBUTION OF THE RECE:-lT FOSSIL MICROTINE RODENTIA OF BRITAIN. STAGE.

SPECIES. Evotomvs hercynicus britannicus, A roicola amph,bius, Microtus agrcsfis hirtus (Lrpus eurnptl?us).

HOLOCENE. (S.E. England.)

Microtus corneri, Arvicola abbotti, M. anglicus, M. arualis, M. agrestis negleetus, M. ratticeps, Euotomvs 2 sp., DicrosfOllYx htnse!i (Ight.), D. gu!r~ lemmus (Lang ), Lemmus elmi (Spermophilus, Och%lla, Lepus variabilis (mglicus).

Ightham Fissures, Langwith Cave, etc.

,.; z

'" 0 v

Crayford and Erith.

!;;

'"

'"'

0...

AND

I

Jfrcrolus niualis, M. ratticeps, Dicrostonyx gulielmi, Lemmus sp. (Spermo' philus).

Clevedon Cave.

l/fierolus malei, M. nivalis, M. ratticeps,

Grays Thurrock.

Microtus agrestoides, 111. ni"aIJides ? A rcicola sp , Eootomvs sp.

High Terrace of Thames Valley.

Mimomys cantianus . Eootomvs sp., Pitymys or Microtus sp. (T,·ogonthtrium).

Upper Freshwater Bed (Cromerian).

Mimomvs intermedius, ilf. majori, M. sauini, Euotomys sp., Pitymys (two or three species). ilfiCrotus (three or four species) (ericetu.' runtonensts, Trogonllurium, Castor, Sciurus sp.).

Lower Freshwater Bed.

Mimomys neuuoni (Casto,' plicidms).

w

z

'"0

u

::i

H

Weybourne Crag.

Norwich Crag.

Afimomys reidi, Af. plioerrnicus.

Jlimom,'s plioemnieus.

In my opmion it IS possible to make from this microtine succession certain deductions with regard to the late Pliocene and Pleistocene distribution of land and water in the west

MARTIN A. C.

HINTON ON

European area, and these deductions are supported by more extended studies of the mammalian palreontology of the periods in question as well as by the stratigraphical and physical evidence. A glance at the table just glven will show that in the late Pliocene period the microtine fauna was exceedingly rich, attaining its maximum development in this period at the time represented by the Crornerian Upper Freshwater Bed; moreover, certain of the genera are represented in this deposit by such a variety of specific forms that we must regard their fossil remains as the sweepings of a vast territory, such as the conjoined Thames-Rhine basins would form, rather than as the memorials of the fauna of so small an area as Norfolk and Suffolk. We may there lore infer that at this time the southeast of England was connected with the continent-a conclusion which has already been arrived at by other observers reasoning from other facts* and which is completely justified by a study of the" Forest Bed" series itself. There can be no doubt that the gap between the Upper Freshwater Bed and the High Terrace of the Thames Valley represents an enormous period of time. During this long interval the ., major glaciation" of north-western Europe, including the whole of the glaciation of south-eastern England, is currently believed to have happened, t a view supported apparently by the fact that near U pminster the deposits of the High Terrace have been seen to rest directly upon the Great Chalky Boulder Clay.j According to the prevalent theory the Glacial" period" was brought about by "a gradual refrigeration of climate at tbe close of the Tertiary ages. This change of temperature affected the higher latitudes alike of the Old and New World. It reached such a height that the whole of the north of Europe was buried under ice, which, filling up the basins of the Baltic and North Sea, spread over the plains even so far south as close to the site of London, and in Silesia and Galicia to the fiftieth parallel (>1' lat it. de. Beyond the limits reached by the northern ice-sheet the climate was so Arctic that snowfields and glaciers spread even over the comparatively low hills of the Lyonnais and Beaujolais in the heart of France." ~ It is thus clear that, if the theory be true, no liquid water could have existed in our island norih of the Thames Valley, and even the country to the south must have been quite incapable of supporting anything like a mammalian fauna of respectable dimensions. The supporters of the more extreme phase of the Glacial theory, feeling the force of these *

Reid, "Geology of Country around Cromer," p. 57, 1882. "Pliocene Deposits of j Hanner, Proc, Geol. Assoc., vol. xvii, p. 449, 1902. ,. Geology of London," vel. It p. 386.1889; Woodward, "Geology of London," 1909, p. II3 . t I-!0lm{'s, (Juart. [ourn; Ceol. Soc., vol. 50, p. 443. 1894. ~ Sir Archibald Geikie," Text-Book of Geology," jrd ed., 1893. p. 1024; ibid., 4th ed., vel, ii, 1903, p. 11302.

Britain." p. IS7, 1890

+ Whitaker,

499

THE BRITISH FOSSIL VOLliS AND LEMMINGS.

considerations, have pictured the cold period (or periods) as a time in which the whole of the higher forms of terrestrial life were exterminated in northern and western Europe, this region being repeopled, as the cold gradually passed away, in the first place by Arctic and Alpine species, such creatures constituting therefore, whether there were one or several interglacial periods, the oldest element s in our existing fauna and flora. * The reasonable expectation of finding in our earliest "postGlacial" deposits traces of an entirely new and incoming terrestrial fauna of Arctic or Alpine character is not realised in Britain. The position of the deposit and the character of its contemporary flint implements prove that the High Terrace Drift belongs to that stage of the Pleistocene sequence which is. known on the continent as the acheuNell. The mamrnalia from this horizon are of an older type and correspond with those found in the deposits of the cheiNen stage. This fauna is quite clearly a relic of the late Pliocene and "pre-Glacial " fauna, and so far as I can judge of continental discoveries, taking into account its position in the Pleistocene series, it stands quite alone in western Europe. Many of the forms, e.g., the High Terrace species of Sus, E!Jltus, Canis, the genera ll£il1lol1lYs and Trogolltlzerzum, are so primitive and appear so thoroughly out of place in a "postGlacial" deposit that any able zoologist of the acheltleen stage, if such there were. must have looked upon the relations then subsisting between the fauna of Britain and that of continental Europe with some of the feelings with which we to-day compare the Malagasy and African assemblages j and it to day one of our ablest observers t can describe the Malagasy rnamrnalia as "living fossils," so then might the same term have been used for the mamrnalia of Britain. Had one of the forms mentioned been exterminated in Britain by the advance of an ice-sheet, a general refrigeration, or any other cause, it would have been gone for ever, because Britain at this time was its last refuge j and therefore it is to my mind inconceivable, in view of this late survival in Britain of Pliocene and in part Lusitanian mamrnalia, that any great and general refrigeration of Britain can have taken place in the time between the deposition of the "Forest Bed" and the formation of the High Terrace of the Thames. The conservative character of the High Terrace mammalia leads me to another inference of importance. In order to exist concurrently with more advanced and progressive species, "living fossils" must enjoy an immunity from active competition with their better equipped relatives, and, in the case of nearly allied forms playing similar parts in the economy of nature, this immunity can only be conferred by insulation. Thus it is that * James Geikie,'· The Great Ice Age/' 1874. p. 506, jrd ed., p. 681; Croll, Climate and l(

Time," p. 058; Woldrtch. Siizb, d Kais, A kat!. t! Wim., Math. Nat., Cl. Bd. 82, Abt. II, p. Go, 1880; Nehring," Uebel" Tundren und Steppcn," Berlin, 1890' t Forsyth Major, Proc, Zool. Soc., 1897, p. 7.8.

50 0

lIIARTI N A. C. HI NTON ON

P roiagus was enabled to survive from th e Miocen e period to Neo lithic tim es in Co rsica and Sardinia ';'; th at B rachyuromys and Gy lllllurollly s linger to-day in Mada gascar t : and th at .Jficrotus orcadensis and its allies continue to inh abit the Orkn ey and Chan nel I slands. t Therefore, after an atten tive study of th e High T erra ce faun a, I conclude that south-eastern En gland, some time after th e dep osition of th e " Forest Bed" series, be came an island , and th at it rem ained isola ted unti l a lat er stage of th e Pl eist ocene perio d tha n that marked by the H igh T errace. I sland fauna s tend to beco me impo verished, firstly in num ber of species, and, a t a later stage, in nu mb er of genera ; whilst the forms which survi ve suffer more or less profo und modifi cat ions of structure as time pro ceed s. In these respects th e H igh T errace mammalia bear out th e inference when compared with th e Cromerian assemblage. The inference is, however, confirmed by several distinct lin es of obs ervation. The N orfolk coast-section show s that th e d epo sition of the "Forest·B ed " series was followed by an intermittent movement of su bsid ence ; § the Upper Freshwater Bed being overlain by th e marine L eda my alt"s Bed, we have in th e so-called Ar ctic Freshwa ter Bed evide nce of a brief retu rn to terrestri al condi tions. The lat ter de posit is succeeded by the Boulde r Clays and con torted Drifts, which, af ter a n exam ina tion o f th e Cro mer sect ions, I am d isposed to regard as mari ne forma tio ns. II In ord er to avoid misapprehension I should state here that it is not denied tha t ice has played an important pa rt in th e collec tio n, com minut ion, and transpor t of the ma terials of the Cro mer T ill, etc. In my opinion , however, th e view which supposes the se dr ifts to have been deposited in a sea into which icebergs from th e north were cont inually brin ging foreign mat erials, satisfac torily accou nts for all the observed characters. Th e incorp oration of much ca lcareous matter in th e deposits, an d its subseq ue nt extensive removal th erefrom by decalcificat ion co upled with the lan dslips, of which the enormous included masses of chalk at West R un ton a nd elsewhe re give evidence , su fficiently explain th e great co ntortio n and partial ind uratio n of these N orfolk dri fts. Further, it will be rem em bered that th e lat e Searles V. Wood , after a mo st exha ustive stu dy of the Engli sh drifts, came to the conclusion that the per iod of the "major glaci ation " of England, represented by th e Crom er Till and the Great Cha lky Boulder Clay, was in fact a period of submergence when only • F or syth Major, Gr ot. MaK., de c. v, vol. i i , p . 463 (1905). Major, P roc, Zo ol. Soc. , 1897, p- 718. t F orsyth Major, A nn. and M ag . N at . H ist. , se ries 7, vo l, xv , p. 324. ~ Clemen t Re id, II Geo logy of Crome r," ]882, p . 58. l! S ome ve ry st riking evidenc e on thes e points is given by Harmer t Proc, Geol , Assoc., vol , x vii, pp. 459-462; Reid , .. Geo logy at Cou ntr y aroun d Cromer : ' p . 93.

+F or syth

THE BRITISH FOSSIL VOLES AND LEMMINGS.

501

the mountainous districts of Britain protruded above the sea-level. Wood carried this view too far in submerging the Weald, and in regarding the High Terrace of the Thames as a marine formation, but, nevertheless, his views as to the submergence of the country north of the Thames basin at this time appear to be right." It is certain that in High Terrace times the base-level of erosion stood nearly 100 ft. higher than it does to-day, and that the land was consequently by so much relatively lower to the sea than it is at present. t Moreover, the fragmentary remains of still older and still higher paired terraces in the Thames Valley teach us that during the early stages of the Pleistocene period the southeast of England was slowly rising from a position still lower than that which it held in High Terrace times.j The presence of Delphinus in the drift of the latter stage leads me also to conclude that at that time the estuary of the Thames was not far to the east of Gravesend. In the case of the Thames and its tributaries, and the other rivers of south-eastern England, we are generally agreed that the erosion of the valleys and the formation of the terraces have proceeded hand in hand, and that consequently an index of the greater or less antiquity of the terraces is afforded by their greater or less height above the stream. Our French and Belgian colleagues, in working out the history of such rivers as the Seine, the Somme and the Meuse, have come to very different conclusions. They have shown that these valleys were excavated almost to their present depth during the Pliocene period,§ since at St. Prest, near Chartres, in the Valley of the Eure-et-Loire, there occurs, at a level of only 80 ft. above the stream, a fluviatile deposit with a typical late Pliocene (Cromerian) fauna comprising Elephas meridionaiis, Rhinoceros etruscus, Hippopotamus and Troj{olltheriu11l, II whilst at Chelles, in the valley of the Marne, there is another river deposit resting practically on the floor of the valley and containing the remains of a fauna very similar to that found in our High Terrace Drift, including among other forms Hippopotamus, Trogontheriu1Jl and a horse approaching Equus stenonis.' The latter deposit is the type development of the che/teen or earliest stage of the French Pleistocene series. Towards the end of the che/leen stage the streams were forced, by a tectonic movement equivalent to a depression of the land, to aggrade their channels and the valleys were filled to a considerable height with alluvium, the highest parts of which deposit correspond in age and position with our High Terrace Drift (=acheuteen stage). The acheuiee»: stage was succeeded, as in England, by an intermittent movement of * Searles V. Wood, Quart. [ourn, Geol. Soc., vol. xx xvi li, P. 667.

+ Hinton and

Kennard, Essex Naturalist, vol. xv, p. 8+_

t Op, cit., p. 67; Proc. Geol, Assoc., vol. xix, p. 80. G. & U. Morttllet, •• Le Prohistoriqwe," Paris, 1900, p. 493; Rutot. II Morrillet, op, cit., p. 34. 'II Op. cit., p. 557. §

50 2

MARTIN A, C. HINTON ON

elevation which enabled the rivers during the mousterien and subsequent stages of the Pleistocene period to re-excavate their valleys and form terraces at lower levels corresponding to our Middle and Third Terraces. Whilst therefore, the English rivers excavated their valleys for the first and only time in the Pleistocene period, the rivers of north-western France and Belgium had already performed their tasks during the Pliocene period, This is an extraordinary difference, of which, so far as I am aware, no explanation has hitherto been given, There is reason to suppose that "between the end of the older Pliocene period and the present day the Anglo Belgian basin has moved as on a pivot, rising in the south and sinking in the north."'" If this be so it is easy to see that streams with a generally west and east course, situate to the north of the pivot, e.e , the Thames, would, during the depression of the northern area in postCromerian and pre-chefleen times, be at base-level and so unable to corrade or excavate their valleys, But on streams, e.g., the Seine and the Somme, flowing from the region to the south of the pivot in a more or less northerly direction, this depression of the northern area would act as an elevation, i.e., it would lower the effective base-level of erosion and would cause the streams in question to corrade their valleys. Conversely, the intermittent movement of elevation, which, beginning in cheflcen or pre-High Terrace times continued until the end of the Pleistocene period, would operate. upon the streams flowing from the southern area towards the northern one as a depression, causing them to aggrade their channels until the moment when the northern area had completely recovered from its depression; thenceforward, if the movement of elevation continued, it would act as a general elevation, causing not only west and east streams, but south and north-flowing streams as well, to deepen their valleys, If these considerations be duly reflected upon they will, in my opinion, bring into harmony the apparently discordant evidence of the English and continental river valleys, and they will also confirm the inference drawn above as to the insular condition of south-eastern England in early Pleistocene times. The uplift which, as elsewhere has been shown, t marked the close of the High Terrace stage, had the effect of placing the south of England in direct communication with the continent during Middle Terrace times. In one of the earliest Middle Terrace deposits-the brick-earth of Grays-we find few indications of any effect upon the fauna, The species of Arnicola occurring at Grays may have been the direct descendant of the High Terrace Mimomys, whilst the other fossil voles of the deposit may very well have been the little-modified progeny of * Harmer, Proc, Geol, .Assoc., vol. XVi~, p. 422, I902. t Hinton and Kennard Essex Naturalist, vol, xv, p.

THE BRITISH FOSSIL VOLES AND LEMMINGS.

503

the older forms of the region. lI£acacus, Hippopotamus, Sus, Eleplzas antiquus and Rltilloceros 1lIegarizinus are certainly to be counted as survivals in this country from the later Pliocene period. But when the Crayford brick-earth came to be deposited a longer period of time had elapsed since the new connection with the continent bad been established, and during this time many immigrants had arrived. The new corners, as is usual, took so kindly to our soil that they ousted the old indigenous forms to a very large extent. Thus at Crayford the voles differ entirely from those found at Grays and they are forms which still have representatives living in western and central Europe. With an eye to what we find in the Ightham Fissures and to other considerations, I infer that the connection of Britain with the continent during the Middle Terrace stage was limited to a junction with France, and that it was from France that we received Microtus nivalis, M. ratticeps, Dicrostonvx guhe/mi, and the other new comers found in the Crayford brickearth. .Ill". nivalis and AI. ratticeps were at this time old forms of the European mainland and they to-day have the most markedly discontinuous distributions among the continental voles." The Middle Terrace stage was brought to a dose by a great movement of elevation which in the end enabled the Thames to excavate its valley to. a depth far below the level of its present bed. This uplift was not a continuous one, for at an early stage of its progress, when the land had been placed some ten or twenty feet higher in relation to the level of the sea than at present, there was a pause marked by the lowest or Third Terrace. t In the deposits of this stage we meet with the remains of two new comers among the mammalia, viz., the reindeer! and the Saiga antelope. After the formation of the Third Terrace the upward movement of the land continued. \Ve cannot at present estimate how great the amount of the elevation was but it appears to have been sufficiently large to lay dry the bed of the North Sea to a latitude somewhere to the north of the Dogger Bank. Little is known of the palreontology of the deposits in the bottom of the buried gorge of the Thames, but from the Dogger Bank and elsewhere in the North Sea, and from the estuary of the Thames, there have been dredged the remains of a typical late Pleistocene fauna including Elephas prillligenius, * For past and present distribution of M, nivalis group (subg. ChitJnomys) see Miller, Ann. and Mog: Nat. Hist. series 8, vel. i. p. 97 (1908) ; Blasius, "Saugethiere Dvutsch-

ands" (r857), p. 362; Hinton, Proc, Geo/. Assoc., vol, x x, p. 39 (lg07). For present distribution of Id . -nuticeps, see Blasius, op. cit., p. 367; Rortg, Arb. a.d, Kais, Anst. f. Landund. Forstwirtsch, Ed. vii, p. 429. t Hinton and Kennard, Essex Naturalist, vol. xv, p. 7I ; Proc. Geol. Assoc •• vol. xix p,83,

t Searles v~ Wood, Quart. Jou.rn. Geol, Soc., vol, xxxviil, p, 704, 712.

MARTIN A. C. HINTON ON

Rhinoceros antiquitatis, Rangijer tarandus, and Ovibos moschatus. '*' The Ightham Fissures, the Langwith and other caves with a similar fauna, appear to me to be clearly referable to this. period. The remains of eight distinct species of vole are found in the deposits of the Ightham Fissures. Of these not one is still living in the south-east of England, and only one, viz., Jf. ratticeps, is a survival from the Crayford horizon, and this occurs but rarely at Ightham. Of the new comers one of the species of Evotomys and JVlicrotus corneri may have come to us from France, because we find near allies of these forms living at the present day in the Channel Islands; all the others appear to have come from Holland, Belgium, and Germany. It was at this date that Ireland, the Hebrides, and the Orkney Islands were placed in connection with Britain and the continent, and received their respective mammalian faunas. With regard to Ireland, the connection with Britain appears to have been maintained only sufficiently long to enable Lepus variabilis lzibernicus (which I regard as the direct descendant of L. var. anglicust), Dicrostonyx, and Lemmus, among the Rodentia, discussed in this paper, to reach it. These are all forms capable of rapidly extending their range-the voles, more stationary in their habits, did not have sufficient time to accomplish the journey. The peculiar Evotomys reached Skomer Island, where it has developed into the living E. skomerensis ; t the llIicrotus agrestis group invaded the Hebrides, where it is now represented by M agr. exsui ; § and M corneri colonised what are now the Orkney Islands, and there was transformed in course of time into M. orcadensis and M sandayenszs.11 Protected from the competition of their relatives by early insulation, these forms have managed to survive in the islands until the present day, notwithstanding that on the British mainland they have long since become extinct. In my opinion it was during this period of maximum elevation that the glaciers were formed in the mountainous districts of Britain, and that those still existing in western Europe acquired their greatest extension. Such a late development of the "Great Ice Age" in Britain would more satisfactorily account for the remarkably fresh condition of the polished and striated rock-surfaces, looking" as if the ice had only recently retreated," ~ and for the slight amount of denudation which many of the mounds of loose glacial rubbish have suffered,** than *

Davies, Gent. Ala,:;., dec. ii, vol. v, p. 64. Roy. Dublin Soc., vol. xi i, new series, p. 26r, I909. Barrett Hamilton, P1'OC. Roy. Irish. Acad., vol. xxiv, section 3, p. 315. § Miller, Ann. aHd Mag. Nat. Hist., series 8, vol. i, P. 201. II Forsyth Major, Ann. and Mag. Nat. Hist., series 7, vol. xv, p. 324; Miner, ibid., series 8, vol , I, p. 199; Hinton, ibid., series 8, vol. vi, p. 35. "'I Sir A. Geikie, .. Text-Book of Geology," 3rd edition, p. 1026. •• Lamplugh, Geographical Journal, ]gog, p. 55.

+ Hinton, Scient. Proc, t

THE BRITISH FOSSIL VOLES AND LEMMINGS.

505

does the prevalent theory which connects most of these phenomena with so remote a period of time as that which a pre-High Terrace glaciation would imply. Moreover there is, although few of us realise it, a complete discord between the view current among British geologists and that held by their continental brethren with respect to glacial chronology. On the continent it is the general opinion that the deposits containing the remains of the "northern" or "Arctic" mammalia mark the culmination of the "Glacial period" ; * and in France, where there is opportunity of studying the relation of these deposits to those Pleistocene beds yielding southern species, it is recognised in addition that the deposits with northern mammalia are not only newer than those with southern forms but that they belong to the later part of the Pleistocene period. t An exactly parallel succession can be traced in England, and here, as abroad, the northern species are restricted to the later Pleistocene deposits; it is, therefore, submitted that the view that the major glaciation of Britain transpired in pre-High Terrace times is unsound and against the weight of the evidence. But even now, notwithstanding the fact that the so-called Arctic mammalia put in a timely appearance to support this late glaciation, it seems to me impossible for there to have been any great and general refrigeration of climate. When we consider that at this very moment, the first possible one for the development of a post-Pliocene "great Ice-Age," our fauna was a far richer one than it is to-day, it must seem absurd to postulate conditions of climate less favourable to mammalian life throughout these islands than those at present obtaining. The existence of Lepus variabilis, Jl.'Iicrotus nivalis, M. ratticeps, Dicro.,toll) 'X, the Arctic Fox, the Reindeer, the Musk Ox, and so forth, in the plains of western Europe during the Pleistocene period has been generally regarded as a proof of the former existence of Arctic severity in this region.I We have already seen that this assemblage of species does not support the" Glacial Period" of orthodox British Geology, because the animals in question did not arrive in Britain until a much later moment in time, when nothing was left of the "great Ice Age" but the "minor glaciation" of Searles V. Wood.s The case of M. nivalis was discussed in a former paper.] and the argument was happily confirmed shortly afterwards by Mr. Charles Mottaz, who discovered the" snow-vole" flourishing in the plain near the French shores of the Mediterranean Sea, where the nearest approach to glacial severity is manifested in all * Nehring, "Ueber Tundren nnd Steppen," P. 155; Woldrich, Sitzb, d. Kais. Akad, d. l-Vien Math. Nat. Cl., lxxxii, Bd. Abt. II, p. 60; Winge, "Om ]ordfundne Pattedyr fra Danmark"; Nordmann, "Danmarks Pattedyr i Fortlden ," 1905, pp. 29, et seq. t Mortillet, "Le Prehtstortque," pp. 54.8-552, etc. t Nehring. " Ueber Tundren und Steppen," p. 60. § Searles V. Wood. Quart. [ourn, Geol, Soc., vol. xxxviii, p. 7'2. II Hinton, Proc, Geol, Assoc., vol. xx, p.SO. PROC. GEOL. Assoc., VOL. XXI, PART IO, 19IO.J 37

506

MARTIN A. C. HINTON ON

but perpetual sunshine, vineyards, and olive gardens.'" More recently I have dealt with Lepus variabilis and have shown that in view of the structure of the English fossil form it cannot be maintained that it required or lived under cold conditions, whilst, in addition, its nearest relative inhabits the Irish plains. t With regard to M. ratticeps the argument is quite parallel with that advanced in the two former cases. The" northern" vole is an old form which has been largely dispossessed of its territory by rather less specialised relatives. It has preserved itself by colonising the more northerly and desolate regions, but even it has managed to leave a living memorial of its former enjoyment of a temperate habitat, since it is now known to live in Holland and North Germany.j The evidence of Dicrostonyx in favour of ice is at first sight much stronger than that given by the three animals just mentioned; but even here, under the genial warmth of a careful scrutiny, it melts away. It is now known that there are many other species of this genus besides the boreal D. torquatus, and that one of them inhabits the by-no-means Arctic island of Unalaska (Lat. N. 54°).§ As already stated, my study of the fossil remains of Dicrostonyx shows that two species inhabited Britain in late Pleistocene times, neither of which can be identified with any living form. We, therefore, can predicate of them no particular climatic requirements; the most we can say is that if the other groups of mammalia which were their contemporaries afford evidence in favour of an inference that the climate was severe they would corroborate. But since the other groups are eloquent against any such inference the extinct species of Dicrostouyx cannot possibly be pleaded in its defence. This brings me to the crux of the whole matter with regard to the so-called Arctic mammalia. Can anyone suppose that either the Banded Lemming, the Polar Hare, the Arctic Fox, the Musk Ox, the Reindeer, or the Esquimaux originated amid the dreary Arctic snows? Each one of these species is the most highly specialised member of the genus to which it belongs, and its comparatively if sometimes only slightly more generalised ancestors are to be sought in the Pleistocene deposits of more temperate latitudes. At some time -after the filling of the Ightham Fissures and before the final separation of Britain from the continent, we received Evotomys hercynicus, Microtus agrestis hirtus, and Arvicola amphibius, together with Lepus europceus. It is not necessary to repeat what was said on a former occasion about the '" Hinton, Sci. Prot. Roy. Dublin Soc., vol. xii, new series, p. 264; Miller, Ann. and Mag. Nat. Hist., ser. 8, vol. I, p. 97.

t Hinton, Sci. Proc, Roy. Dublin. Soc., vol. xii, new series, p. 260. t Nehring, Sitzb, d. Naturforsch, Ges., 1899, P. 57; Rorig, Arb. a.d, Kaie, Anstalt, jl'Y Land-und Forstunrts, Bd. vii, p, 429, 1909. § Hensel, Zeits, d. Deutsch Geol, Gesell, Bd, VII, p, 497; Nehring, ., Ueber Tundren und Steppen," p. 23; Merriam, Proc, Wash. Acad. Sci., ii, p. 25.

THE BRITISH FOSSIL VOLES AND LEMMINGS.

507

competition of species, '*' but to-day these four forms alone are found living in the south-east of England and they have thus completely replaced those related species whose bones are found in the deposits of the Ightham Fissures. Although our standpoints are different and our views as to the origin of the "Arctic" mammalia sometimes divergent, it affords me great satisfaction to be able to support Dr. Scharff in his protest against the extreme phase of the Glacial theory. Further, the researches outlined in this paper confirm Dr. Scharff's opinion that the oldest element in our fauna and flora is the southern or Lusitanian one. The Lusitanian mammalia have long disappeared from Britain, but more lowly forms of Lusitanian life still linger, having survived in these islands the vicissitudes of "extreme glaciation," "Steppe and Tundra-like conditions" and so forth in a really remarkable way.t NOTE.-I regret that when the above was written I was ignorant of, a very important paper by Mr. Stejneger on "The Origin of the so-called Atlantic Animals and Plants of Western Norway" (Smithsonian Miscellaneous CollecNons, xlviii, 1907, pp. 458-5 I 3). I think the statements made here with regard to the M. agrestis group, etc., go far to support Mr. Stejneger's view.-M.A.C.H., II/IO/I9IO.

,. Proc, Geol. Assoc .• vol. xx, p. 54. Scharff, "History of the European Fauna" (1899); "European Animals" (1907).

t