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Show 470 ON FOSSIL A R V I C O L I D A . [June 16, from the Breche de Coudes, with twelve angles to the first lower molar. Counting the anterior extremity as an angle, this agrees with the present animal; and the rest of his description applies so well as to leave no doubt that he had a Lemming of this species before him. Three years later Hensel recognized this species among fossils from the diluvium of Quedlinburg, in Saxony, in the Mineralogical Museum of Berlin. In this country we discovered it in some numbers in 1865 in the drift-deposits atFisherton; and next year Mr. W . Flower sent us some specimens for identification, procured from Wookey Hole. In 1870 M r . Sanford recognized part of a skull in the Taunton Museum as only differing from recent specimens in being slightly larger. At the same time he referred six lower jaws in the same collection to a new species of Arvicola, which he provisionally named A. gulielmi, remarking that they might prove the same as Pomel's A. ambiguus. Dr. Forsyth Major has since pointed out that these appear to be the lower jaws of the present species-a conclusion at which we had independently arrived, and in which we believe Mr. Sanford now fully concurs. Remains from Hohlenstein, near Ulm, are described by Dr. Forsyth Major; and a fine skull from Eppelsheim, near Darmstadt, is in the British Museum. Middendorff has clearly shown (' Sibir. Reise,' ii. th. 2, pp. 87- 99) that M. hudsonius, Pall., M. grcenlandicus (Trail), and Lemmus ungulatus, Baer, are all identical with M. torquatus, whose range may therefore be described as circumpolar. It is found in the Hudson-Bay countries, in Novaja Zemlja, from the White Sea to the Obi, in Taimyrland, on Baer Island, and Novaja Siberia, and from the Lena to the Jana. It appears to be very rare in Greenland (cf. Brown, P. Z. S. 1868, p. 349), and is not found in Russian Lapland. Parry found a skeleton in N . lat. 82°, while it reaches its most southern point in Unalaska, under N . lat. 54°. In postpliocene times it appears to have extended at least as far south as Germany, England, and the basin of the Loire. In this species the prisms of the posterior molars are not compressed and twisted as in the typical Myodes, but are placed regularly as in Arvicola; and Hensel has consequently separated it as a new genus, under the name Misothermus. The pattern, which appears to be very constant, is:- Upper I. 7 spaces, 8 angles. Lower I. 9 spaces, 11 angles. ,, 11. 0 ,, 7 „ ,, 11. o ,, 7 ,, „ HI. 6 „ 8 „ „ III. 4 „ 6 „ W e have compared recent and fossil skulls in the British and Taunton Museums and in our own collection. 9. MYODES LEMMUS (Linn.). 1855. Myodes lemmus, Hensel, Zeits. d. Deutsch. Geol. Ges. vii. p. 486, pi. xxv. figs. 10, 11, 15. 1870. Lemmus norvegicus, var., Sanford, Q. J. Geol. Soc. xxvi. p. 125, pi. viii. figs. 3 a, b. |
