62 



Sirenia — Manatee, Rhytina, etc. 



Pier-case, 

 No. 21. 



Skeleton of 

 Rhytina. 



Stand N. 



and either five or six cheek-teeth in each jaw, or 24 molar teeth and 

 two tusks. The Halicore or "Dugong" has only twelve molar 

 teeth and two tusk-like incisors in the upper jaw. The adult 

 Rhytina had no teeth, the palate and anterior portion of the 

 lower jaw being provided with horny plates of hardened epithe- 

 lium, which served in lieu of teeth for masticating the seaweed 

 which formed its food. The manatee inhabits the west coast 

 and the rivers of tropical Africa, and the east coast and rivers of 

 tropical America, the West Indies and Florida. The dugong 

 (Halicore) extends along the Red Sea coasts, the shores of 

 India, and. the adjacent Islands, and as far as the north and 

 eastern coasts of Australia. 



Fig. 73.— Skeleton of the living "Manatee" (Mahatus americanus), from the 

 Eiver Amazon. 



The most remarkable Sirenian is the Rhytina gigas (Rhytina 

 Stelleri), or " Steller's Sea-cow r ," once common along the shores 

 of Behring's and Copper Islands, near Kamtschatka, and 

 seen alive by the naturalist Steller in 1741. This is by far 

 the largest of the Sirenia, and when full grown, it is said to 

 have attained a length of 25 feet, and a weight of from three 

 to four tons. 



The Sirenia pass their whole life in the water, being denizens 

 of the shallow bays, estuaries, lagoons, and large rivers ; but 

 they never venture far aAvay from the shore. Their food con- 

 sists entirely of aquatic plants, upon which they browse beneath 

 the surface, as the terrestrial herbivorous mammals feed upon 

 the green pastures on land.* 



When Steller came to Behring's Island in 1741, the Sea- 

 cows pastured in the shallows along the shore, and collected in 

 herds like cattle. As they fed, they raised their heads every 

 four or five minutes from below water in order to breathe 

 before again descending to browse on the thick beds of sea- 

 weed which surround the coast. 



* The large seaweeds called Laminarice grow in water at or just below 

 low-water ; they are nutritious and are eaten by animals. They abound in 

 the North Pacific Ocean. Ruprecht, in his account of tbe Algae of the North 

 Pacific, records eight species of these large weeds growing in the Sea of 

 Ochotsk, on the shores of Kamtschatka, and the north of North America. 



