. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. 7S Biology of the Vertebrates Of-this order only two genera (Figs. 72 and 73) are represented by living animals, that are separated from each other on the globe about as far as it is possible, since "manatees" representing the genus Trichechus inhabit the rivers of the northeastern coast of South America and beyond as far north as the Everglades of Florida; while the "dugong," Halicore, lives in the Red Sea and Indian Fig. 72. A
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. 7S Biology of the Vertebrates Of-this order only two genera (Figs. 72 and 73) are represented by living animals, that are separated from each other on the globe about as far as it is possible, since "manatees" representing the genus Trichechus inhabit the rivers of the northeastern coast of South America and beyond as far north as the Everglades of Florida; while the "dugong," Halicore, lives in the Red Sea and Indian Fig. 72. Atlantic sea cow or manatee, Fig. 73. Trichechus. (After Dugmore.) Halicore. Dugong, or Indian Ocean sea cow, (After Schniid.) Of the 7 fossil genera, one, Rhytina stelleri, or Steller's sea cow, has been extinct less than 200 years. This species first became known in 1741 when Steller, a Russian whaler, was shipwrecked upon a small group of islands in Bering Sea. He was saved from starvation by finding a rookery of these large sea cows upon which he and his crew fed until rescued. During the following quarter of a century Russian whalers with human greed and stupidity hunted these valuable food animals to extinction, for Nordenskiold, who visited the islands in 1768, reported that the last individual of the colony had been killed. This species of sea cow has never been found elsewhere. (15) cetacea.—The cetaceans, or whales and their allies, among which are to be found the largest animals that ever lived, include the levia- thans of the oceans. The ancestry of the cetacea is a puzzle for the solution of which fossils give scanty aid. Compar- ative anatomy shows that they bear unmistakable hall-marks of mammalian forbears, such as breathing air by means of lungs and feeding the young upon milk. Since the mammalian plan undoubtedly originated with land forms, cetaceans must have undergone profound modifi- cation in order to become adapted secondarily to a marine existence where
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