URSUS SPELEUS. 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 by 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 feetus, 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 fcrox), 
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 
