350 



COMPARATIVE ZOOLOGY. 



PIG. 343 Troop of Dolphins, with Manatee iu the distance. 



one. They have a narrow brain ; bristles scantily cover- 

 ing the body ; and nostrils placed on the snout, which is 

 large and fleshy. The living representatives are the Ma- 

 natee, of both sides of the tropical Atlantic Ocean, and the 

 Dugong, of the East Indies. 



9. Proboscidia. This race of giants, now nearly ex- 

 tinct, is characterized by two upper incisors in the form of 

 tusks, mainly composed of dentine (ivory). In the extinct 

 Diriotherium the tnsks projected from the lower jaw; and 

 in the Mastodon, from both jaws. Canines are wanting. 

 The molars are few and large, with transverse ridges (Ele- 

 phant) or tubercles (Mastodon). The cerebrum is large 

 and convoluted, but does not cover the cerebellum. The 

 skull is enormous, the size arising in great measure from 

 the development of air -cavities between the inner and 

 outer plates. The nose is prolonged into a flexible trunk, 

 which is a strong and delicate organ of prehension. There 

 are four massive limbs, each with five toes incased in 



