SEALS. 
77 
dentition being that of animals living as much on vegetable as on 
animal food. They are wholly plantigrade, and their claws are non- 
retractile. They are a remarkably homogeneous group, there being 
but few differences between them other than their relative sizes and 
the proportions of their teeth. 
Skeletons are mounted of Brown [Ursus arctos) and Polar 
Bears [U. maritimus), besides a large series of skulls of different 
species. 
The second great division of the Carnivores, the Carnivora 
Pinnipedia, or Seals, is strikingly modified in general form, yet 
shows clearly its relationship to the Land Carnivores, and especially 
to the Bears. The skeleton of a typical Seal (fig. 35) is elongate, 
with a small skull, no clavicles, rudimentary tail, and limbs of 
which the upper bones are very short, while the hands and feet 
are long, with five well-developed toes. The hind legs are turned 
backwards, so that the two soles are opposed to each other when 
the animal swims, the two together forming a single posterior 
swimming-paddle. Their action is similar to that of a person 
propelling a boat with a single oar worked from the stern. 
The skull (see fig. 36) has no postorbital processes, and the 
posterior teeth are not differentiated in the same way as those of 
Fig. 3G. 
the Land Carnivores, there being no specialized sectorial tooth, 
nor any flat tubercular teeth at the back of the mouth, all the 
teeth being long and sharp, with the points directed towards the 
throat, and forming admirable instruments for catching and hold- 
