FEET AND KHINARIUM OF THE POLAR BEAR. 159 



13. On the Feet and Rliinarium of the Polar Bear 

 {Tlialarctos maritimus). By R. I. PocoCK, F.R.S., 

 F.Z.S. 



[Eeceived February 20, 1923 : Read February 20, 1923.] 

 (Text-figure 1.) 



The fore feet resemble in a genei^al way those of all the 

 northern species referred to Ursus and Euarctos in having a 

 single small isolated carpal pad entirely surrounded by hair and 

 sepai-ated from the plantar pad. The pads of the hind foot are 

 very similar to those of the fore foot, but the digitals are a little 

 smaller and the plantar a little larger, although of the same 

 width. A point in which the hind foot of Thalarctos differs 

 from that of all other genera of Ursidse is the extent to which 

 the metatarsal area is overgrown with hair, reducing the meta- 

 tarsal pad to a small elliptical pad occupying nearly the same 

 position as, and only a little larger than, the carpal pad of the 

 fore foot. In the othei' genera the metatarsal area is either 

 wholly naked or is merely invaded on the inner side by a 

 narrow tract of hair along the groove marking the division 

 between the plantar and metatarsal pad. As subsidiary differ- 

 ences it may be noticed that the carpal pad is altogether smaller, 

 and the plantar pads of both fore and hind foot shorter, than in 

 the rest of the genera. 



The digits of both fore and hind foot are separable by tolerably 

 equal spa,ces as in Ursus arctos, and, as in that species, the inter- 

 digital integument extends approximately half-way along the 

 digital pads. 



The rhinarium resembles closely that of Ursus arctos, hon-ibilis, 

 Uuarctos americanus, and Selenarctos tibetanus. It is everywhere 

 sharply circumscribed by hair, though less so on the upper lip 

 than above. In profile view the internarial septum is not 

 concealed by the lateral border of the nostril ; and there is a 

 deep, smooth infranarial area on each side, marked by a shallow 

 groove which diverges outwards and upwards from the middle 

 line to the nostril. Their point of union in the middle line is 

 crossed by another shallow groove, which descends vertically 

 from about the middle of the internarial septum to the ill- 

 defined philtrum, dividing the hairs of the vipper lip. 



The ears are in no respect degenerate, and resemble those of 



