URSUS SPEL^EUS. 87 



out the difference in the proportion of length to breadth in 

 the skull of an old White Bear, and in that of the great 

 Cave Bear ; the individual skulls which he compared are 

 still preserved in juxtaposition in the Museum of the 

 College of Surgeons, as they were left hy Hunter, when 

 removed by death from the last and richest field of his 

 extensive and various researches. 



This difference in the proportions of the skull, though 

 one of the most striking between the fossil and recent 

 species of Bears, is not the only one. The last molar tooth 

 of the upper jaw in the White Bear (Ursus maritimus) 

 has a smaller antero-posterior diameter, and a narrower 

 posterior termination. The interspace between the ante- 

 penultimate molar and the canine tooth presents the re- 

 mains of two sockets, one near the molar, the other near 

 the canine, which in young, but full-grown Polar Bears 

 contain small and single-fanged premolars. The youngest 

 specimens of Cave Bear which I have seen, exhibit no trace 

 of either of these small premolars, or of their sockets ; 

 they doubtless existed in the foetus, but normally were 

 very soon lost ; the exceptions are extremely few in 

 which their traces are visible in the jaws of full-grown 

 Cave Bears. The posterior palatal foramina are situ- 

 ated opposite the middle of the last molar tooth in the 

 skull of the White Bear, but opposite the interspace 

 between the penultimate and last molars in the skull 

 of the Cave Bear. The zygomatic arches are wider and 

 shorter, and the base of the zygomatic process behind 

 the glenoid cavity is more horizontal in the White Bear 

 than in the Cave Bear. The Grisly Bear (Ursus ferox), 

 a larger species than the White Bear, and unknown to 

 Hunter, agrees with the Cave Bear in the great propor- 

 tional size of the last molar tooth, but the interspace between 



