ll' : MAMMALIA. 



of the sea. On the other hand, the American 

 la mail tin is still undergoing the transition, and 

 feels as comfortable in the sea as it does in the 

 lowest currents of large streams. The dugong of 

 tern Africa lias, however, remained perfectly 

 faithful to its old, hahitnnl clement. An interest- 

 ing example- of the occurrence of a mammal in an 

 inland lake is the dog-fish of the Caspian Sea. It 

 in fact, simply left there. That this large 

 of water was at one time connected with the 

 sea is a long since established fact. 



By this remark, and a return to the geological 



<even though it be to a most recent past), we 



iin entered the only path which leads to 



til.- understanding of all the geographical configu- 



ns of the present, more particularly to the 



ibution of the organisms, and above all to that 



of the land animals. The difficulty of meeting 



with closely related species, orders, and larger 



groups, in regions lyinj^ far apart and separated 



by hi.uh chains of mountains or impassable oceans, 



tfon's days, been quietly settled with 



the word ' rioariate,' which proves anything but a 



true understand! 1 matter. AVhen it is said 



i iate ' in Australia for the 

 distributed on the other continents, 



