1885.] DR. ST. G. MIVART ON THE ARCTOIDEA. 389 



ia 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 thau 

 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 cinguluin. The first upper true molar is shaped like 

 that of Taxidea, only that it has a less predominantly broadened 

 villus, and that all its tubercles are rouiided ; 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 thau 

 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 brain ^ differs from that oi Lutra in having the crucial sulcus 

 placed more forwards, and the Ursine lozenge larger and more con- 

 spicuous. 



Ursus". — This well-known genus of about ten species ranges from 

 the Arctic region southwards. For the main part confined to the 

 Palsearctic and Nearctic regions, it descends to Africa north of the 

 Sahara, to Ceylon and the Indian Archipelago, and to Peru and 

 (;;hili. 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. 



^ See Albertus Magnus, de Anim. lib. xxii. p. 183 : Linn. S. N. 169 ; Pallas, 

 Zoogr. Eoss.-Asiat. i. p. 64 ; Gaielin, 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 ; Raffles, Linn. Trans, xiii. p. 254 ; 

 Schreber, Saug. p. 513 ; De Blainyille, Ost6og. Urmis ; Cuvier, Os8 Fofsiles, iv. ; 

 P. Gervais, Mamm. 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. ; 

 Gray, P.Z. S. 1864, p. 680; Cat. Carniv. Brit. Mus. p. 215; Sclater, P. Z. S. 

 1862, p. 361, pi. 32; 1864, p. 374, 1867, p. 817; Swinhoe, P. Z.S. 1863, 

 p. 380 ; Hempr. & Ehrenb. Symb. Physicae, i. t. i. ; Eadde, Melanges Biologiques 

 de St. Petersb. iii. p. 677. The above genus Ursus includes the Thalassarctos, 

 Myrmarctos, and Helarcfos of Gray. 



Proc. Zool. Soc— 1885. No. XXVI. 26 



