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Show 1885.] DR. ST. G. MIVART ON THE ARCTOIDEA. 389 in having only four lower incisors. The molars all have their tubercles curiously rounded. The fourth upper premolar has the antero-posterior length of its inner and outer sides more equal than heretofore, and has two central subequal cusps and two inner ones, whereof the anterior is very much indeed the larger. There is also an internal cingulum. The first upper true molar is shaped like that of Taxidea, only that it ha3 a less predominantly broadened villus, and that all its tubercles are rounded ; it has a small external, and an exceedingly large internal, cingulum. It has also two external cusps, whereof the anterior is the larger, and three internal ones. The lower molars are similar to those of Lutra, only they are more broadened out and flattened and have more rounded tubercles. The first lower true molar has a small anterior cusp, then two large ones, one external and one internal, followed by a large talon. The second true molar is broader than long. In the milk-dentition the first upper deciduous molar is a very small, conical tooth. The second is more sectorial than is the third premolar, having no postero-internal tubercle or any internal cingulum. It has one anterior cusp, with a pair of cusps (one internal and the other external) behind it. The third deciduous molar is very like the fourth premolar, but it has a relatively bigger internal cingulum and a large postero-internal tubercle, and thus it so far approximates towards the form of the first upper true molar. The third deciduous inferior molar is more Otter-like than is the fourth lower premolar, but it has a larger (especially broader and above all posteriorly broader) talon, which forms rather more than half of the entire tooth. The three outer cusps, however, are blunter than in Lutra, though they are not so blunt as are the permanent molars of the adult animal. The brain1 differs from that of Lutra in having the crucial sulcus placed more forwards, and the Ursine lozenge larger and more conspicuous. Ursus2.-This well-known genus of about ten species ranges from the Arctic region southwards. For the main part confined to the Palaearctic and Nearctic regions, it descends to Africa north of the Sahara, to Ceylon and the Indian Archipelago, and to Peru and Chili. The genus is, however, entirely unrepresented in the Australian and Ethiopian region, and has only one species (U. 1 P. Z. S. 1869, p. 20. 2 See Albertus Magnus, de Anim. lib. xxii. p. 183 ; Linn. S. N. 169; Pallas, Zoogr. Ross.-Asiat. i. p. 64 ; Gmelin, S. N. i. p. 100 ; Fischer, Syn. Mam. p. 143; Horsfield, Linn. Trans, xv. p. 332; Temm. Fauna Japonica; Desm. Mamm. p. 165 ; Richardson, F. B. Amer. i. p. 14 ; Rafiles, Linn. Trans, xiii. p. 254 ; Schreber. Saug. p. 513 ; De Blainville, Osteog. Ursus ; Cuvier, Oss Fofsiles, iv.; P Gervais, M a m m . ii. p. 10 ; Wagner, Supp. ii. p. 130 ; Buffon, Hist. Nat. viii. p 248, pi. 31-33, xv. p. 128, Supp. iii. p. 200, pi. 34; Baird, Mam. N. Am.; Grav P Z S 1864, p. 680; Cat. Carniv. Brit. Mus. p. 215; Sclater, P. Z. S. 1862,' p. 361, pi. 32; 1864, n. 374, 1867, p. 817; Swinhoe, P.Z.S. 1863, p. 380 ; Hempr. & Ehrenb. Symb. Physicse, i. t. i. ; Radde, Melanges Biologiques de St. Petersb. iii. p. 677. The above genus Ursus includes the Thalassarctos, Myrmarctos, and Helarctos of Gray. PROC. ZOOL. Soc-1885, No. XXVI. 26 |