SIRENIA OR SIREtflANS. 113 



and cements them together. The grinders succeed each 

 other from behind forward ; and there is never more than 

 one, or two partially, on each side of both jaws at the 

 same time ; for the series is in constant process of shed- 

 ding and replacement. The total number of grinders 

 which follow one another on each side of both jaws is 

 seven, or at least six. 



In both hemispheres the superficial deposits abound 

 with bones of elephants which are now extinct. An ele- 

 phant, covered with long, thick hair, and wholly unlike 

 anything now living, was found encased in ice on the 

 coast of Siberia. It was in such a state of preservation 

 that dogs fed upon the flesh, although it is probable that 

 it had been there thousands of years. 



The Mastodon is an extinct proboscidean whose remains 

 abound in the superficial accumulations of America, as 

 well as in those of the Old World. In general appearance 

 the Mastodon was much like the elephant, but differed 

 from the latter in the grinders, the crowns of which are 

 studded with large conical points. The Mastodon was 

 vastly larger than the Elephants of to-day. 



SUB-SECTION VIII. 

 THE ORDER OF SIREISTIA OR SIREXIANS. 



The mammalia of this order are more or less fish-like, or 

 more nearly whale-like, in general appearance, and are 

 popularly known as Sea-Cows, Dugongs, and Stellers. 



They are specially fitted for progression in the water. 

 Their forward limbs are paddle-like, and they have neither 

 hind limbs nor pelvis, and their tail is flattened horizon- 

 tally. In these respects they are like the whales ; and 



