MANATID^E. 



593 



A third genus, Rhytina, formerly lived on the shores of Bearing's 

 Island, but has been extinct for 'more than a century. 



In Flower and Lydekker's ' Introduction to the Study of Mam- 

 mals,' each of the genera named is classed as the type of a family. 



Genus HALICORE, Illiger (1811). 



Nostrils on upper part of muzzle. Tail crescent-shaped, concave 

 behind. Pectoral fins ovate. No nails on digits. 



The thick rostrum and the mandibular symphysis bent down- 

 ward. Teeth altogether, i. |, m. Q ; but only two upper incisors 

 are found in adults and two or three molars on each side above 



Fig. 195. Skull of Halicore dttgong. 



and below. The adult incisors are rootless, straight, tusk-like, 

 large in the male, not exserted in the female. The anterior molars 

 are circular in section, and increase in size backward, the last 

 appears as if formed of two cylinders joined together ; the anterior 

 molars fall out before the posterior molar appears above the gum, 

 All are rootless and destitute of enamel. 



Three species have been described ; but it is doubtful whether 

 H. tabernaculi, from the Red Sea, and If. australis, from Australia, 

 are distinct from the Indian species //. duyonrj. 



