xxv] SIRENIA 699 



adaptation to a similar mode of life, the Sirenia differ from the 

 Whales so profoundly that no direct relationship can be assumed to 

 exist between the two groups. The Cetacea are all flesh-eaters but 

 the Sirenia are vegetable feeders and browse on sea-weeds and other 

 water-plants. As these habits necessitate their staying under the 



FIG. 350. Skull of African Manatee, Manatus senegalensisy.\ t 



water for some considerable time, the bones are heavy and solid, 

 quite different in structure from the bones of Whales, which are 

 much more spongy in texture. The skull is long, not rounded, and 

 the face bones are only moderately developed. The parietals are 



FIG. 351. Front view of head of American Manatee, Manatus americanus, 

 showing the eyes, nostrils and mouth. A. with the lobes of the upper lip 

 divaricated. B. with the lip contracted. From Murie. 



not pushed aside by the development of the supra-occipital; the 

 supra-orbital plate of the frontal is small, while the orbit is large 

 and bounded below by a very powerful jugal. The teeth are broad 



