ARCTIC ZOOLOGY. 109 



in the water. Destitute of hinder feet, they fall away re- 

 markably from the previous orders of mammalia ; but the 

 spine, as in those animals, runs the full length of the 

 body, terminating only in the angle where the portions 

 of the tail divide. The tail is distinct from that of fish, 

 being unfurnished with bone ; being formed of a com- 

 bination of cartilaginous, tendinous, and fatty substance ; 

 and being placed horizontally. Ditferent from fishes also, 

 animals of the cetaceous order are provided with instru- 

 ments similar to fins, but of bony construction, much re- 

 sembhng the fore leg of quadrupeds, which to them sup- 

 plies the use of the pectoral fin of fish, and of the fore arm 

 of animals accustomed to grasp familiar or hostile objects. 

 A stronger resemblance to fish is observable in others, 

 having a dorsal fin ; but when this comes to be examined, 

 it is found to be an elevation of spinous processes with 

 the common integuments, and not moveable in the manner 

 in which fishes employ that appendage. Cetaceous animals 

 possessed of the dorsal fin are usually hostile to those de- 

 stitute of it ; and those furnished with teeth are very re- 

 markable for predaceous character. Like quadrupeds 

 they are all viviparous ; and from their habit of suckling 

 their offspring, are properly classed with the mammalia. 



The head of the balaena mysticetus is about one third 

 of the length of the body, but often exceeds that dimension. 

 The remaining two thirds are evenly divided by the parts 



