468 



DE. H. WOODWAED Olf Al^ ALMOST 



In Manatus senegalensis (fig. 5) there are milk-incisors present - ^ ^ ? 

 wliich disappear. The molars amount to J|^ ; the upper molars 

 have two ridges and three roots ; the lower mandibular series have 

 an additional posterior ridge or talon, and only two fangs. 



Pig. 5. — Dentition of Manatus senegalensis. 

 West Coast of Afnca. 



A. Left half of the palate. 



B. Part of left ramus of mandible. 



The teeth drop out in front, and are renewed from behind as in 

 the Proboscidea. 



This extreme variation in the number of the teeth from 2 to 48 

 is exactly paralleled in the Cetacea, in which we have many eden- 

 tulous species (Balaenidse) ; others with only two teeth present (Zi- 

 phioid Whales); others again with very numerous teeth (Delphinidse). 

 All the earlier voyagers confounded the Sirenia with the Seals, 

 and the Rhytina with the Morse or Walrus. 



In 1811, Illiger separated the three genera — Manatus, Halicore, 

 and EJiytina, under the name Sirenia, and placed them between 

 the Seals and the Cetacea. They are now placed by Prof. Plower 

 and other naturalists between the Ungulata and the Cetacea. 



The following is a List, with their distribution, of the existing 

 species of the order Sirenia : — 



Manatus senegalensis, Desmarest (the African Manatee), inhabi- 

 ting the west coast of Africa from about 16° JST. to 10° S. lat. 

 and as far into the interior as Lake Tchad ; and according to 

 native accounts, to the Eiver Keebaly, 27° E. long. 

 Manatus latirostris, Harlan (the West Indian Manatee), inhabi- 

 ting the creeks, lagoons, and estuaries of the West Indian 

 Islands and coast of Plorida. 

 Manatus americanus (the Brazilian Manatee), inhabiting the coast 

 as far south as about 20° S. lat., and the great rivers of Brazil 

 almost as high as their sources. 

 HaJicore tahernaculi (the Dugong) inhabiting the Eed Sea and the 



east coast of Africa. 

 Halicore dugong, inhabiting the Indian Sea, Ceylon, Bay of Bengal, 



Indo-Malayan Archipelago, and Philippine Islands. 

 Halicore australis, the coasts of Eastern and jN^orth Australia. 



