720 MAMMALIA. 



character. Outside the Marsupials it is only known else- 

 where in the Madagascar tailless hedgehog {Centetes), where 

 there are sometimes four upper molars. In the dog the 



dental formula is 25i? . the upper carnassial or fourth pre- 



3*43 rr . 



molar has a stout bilobed blade, the lower carnassial or first 

 molar has a compressed bilobed blade. The skull is more 

 elongated than in the cats ; the orbits are very widely open 

 posteriorly ; the clavicles are very small ; the limbs are 

 digitigrade ; there are five toes on the fore-feet, but the short 

 thumb does not reach the ground ; there are only four toes 

 on the hind-feet, but in domestic dogs the rudiment of the 

 hallux is sometimes enlarged as the "dew-claw"; the claws 

 are non-retractile and blunt. 



(3) Arctoidea — Bear-like Carnivores. 



The tympanic bulla shows no trace of an internal septum ; the 

 paroccipital process of the exoccipital is quite apart from the ■ 

 bulla, and widely separated from the mastoid process of 

 the periotic. The limbs are plantigrade or sub-plantigrade, 

 and always bear five toes. There is no caecum. 



Family Ursidae — Bears. The molars have broad tuberculated crowns 

 used for grinding. The three anterior premolars are usually 

 rudimentary. The auditory bulla is depressed. In relation to 

 the character of the teeth, it should be noted that the diet is at 

 least in part vegetarian ; even the polar bear eats herbs in the 



summer. Ursus, *-^-, absent from Ethiopian and Australian 



regions, represented in the Neotropical region by only one 

 species, elsewhere widespread. 

 Family Procyonidse — The Himalayan Panda (SElurus fulgens), the 



American raccoon (Procyon). The true molars are -. 



Family Mustelidae — The otter (Lutra), the sea-otter (Latax lutris), 

 the skunk {Mephitis), the badger (Meles), the ratel (Mellivora), 

 the marten, sable, polecat, stoat, weasel {Mustela). The true 



molars are — or—. 



Sub-Order Pinnipedia. iSeals, Eared Seals, and Walruses. 



Marine Carnivores, unable to move readily on land, but coming 

 ashore for breeding purposes. They feed for the most part on fish, 

 molluscs, and crustaceans. Absent from the tropics, they are repre- 

 sented on most of the coasts in temperate and Arctic zones. Many are 

 markedly gregarious. 



The upper parts of the limbs are included within the skin and general 

 contour of the body. There are five well-developed digits connected 

 by a web of skin. In the hind-foot the first and fifth toes are generally 

 stouter and longer than the rest. There are no clavicles. The tail is 

 very short. 



The small milk-teeth are absorbed before or immediately after 



