No. 442.] 



HABITS 



659 



animal is quite aquatic in its habits. In Chimarrogale, 

 gale and Crossopus there is a stiff fringe of hairs which m 

 the same purpose as the compression of the tail. Th« 

 vertebrae are flattened laterally in Ornithorhynchus, 

 Halicore, and some Cetacea. 



II. In the limbs, which at first play such a part in 

 tion in the water, we should expect to find marked ad; 

 Naturally those forms which move about occasionally u 

 land have the limbs less modified than those which have 

 more completely aquatic, as progress upon the land call 

 entirely different form of limb from that which is most 1 

 the water. In some animals semi-aquatic habits ha' 

 assumed while as yet no modification of the limb ha 

 place. Thus in the water-vole, ML- rot us amphibius, thi 



muskrats, have only rudiments of webs at the base of t 

 while the minks have the toes partially webbed. The 

 and the water-opossum. C'hironectes, have the hind fee 

 and fully webbed, while in the otters, the sea-otter and tl 

 bill, Ornithorhynchus, both feet are webbed to the cla 



Steller's sea-cow, Rh 

 whales reach the clii 

 side of the body bee 



