260 



FIRST LESSONS IN ZOOLOGY. 



In tlie walrus (Fig. 359) the upper canine teeth form 

 tusks by which the creature can climb upon cakes of ice, 

 or dig for clams, its principal food, in the deep mud of 

 bays. 



While the Carnivora are destructive and often injurious 

 to the domestic animals, they are economically valuable, 

 especially the marten family, for their fur. 



The true or land Carnivora begin with the bears and end 

 with the lion and other cats. The bears are the least 

 specialized of the order, as they walk on the sole of the en- 



FiG. 259.— Skeleton of the Walrus. 



tire foot, whence the term "plantigrade" applied to them; 

 whereas the cats, the more agile of the flesh-eaters, walk 

 on their toes. 



The bears have a thick, clumsy body, with a rudimen- 

 tary tail, and the molar teeth are broad and tuberculated, 

 so that they can live indifferently on fish, insects, or ber- 

 ries. Our North American species are the polar bear 

 ( Ursus maritimus) and Ursus arctos, with its varieties of 

 brown, cinnamon, and grizzly bears; and the true black 

 bear ( Ursus Americanus). The black bear weighs from 

 two to four hundred pounds, is common in the wooded 

 or mountainous parts of the country, and is destructive 



