6 CETACEANS. 



grampus, feeds on seals and some of the smaller Cetaceans, and is indeed the only 



member of the order which subsists on warm-blooded animals, many of the toothed 



Cetaceans prey on fishes of various kinds, while others devour small crustaceans, 



jelly-fish, and the molluscs known as pteropods. The food of many of the larger 



species consists almost exclusively of squids and cuttles ; and so small are the 



animals on which the Greenland whale feeds, that it is commonly said that this 



species would be choked if it attempted to swallow a herring. 



Although the killer is renowned for the ferocity of its disposition, 



the majority of Cetaceans are harmless and timid animals, usually 



associating together in companies known as " schools," which may sometimes 



comprise several thousands of individuals. As a rale, the members of a school are 



said to display an affectionate disposition to one another: and numerous anecdotes 



attest the strong attachment and solicitude displayed by the females towards their 



offspring. Some of the tinner whales appear to produce two young at a birth not 



uncommonly, but the usual number is one. 



Existing Cetaceans are divided into two great primary groups, 

 Classification 



the one comprising the true, or whalebone whales, in which the place 



of teeth is taken by baleen or " whalebone." and the toothed whales, characterised by 



the presence of functional teeth, at least in the lower jaw. These two groups 



differ from one another in man}- important respects, and if they an' derived from 



a single stock, their common ancestor must have existed at a comparatively remote 



epoch. Dr. Ktikenthal is, however, of opinion, that the whalebone and the toothed 



whales have originated independently of one another from totally distinct groups of 



terrestrial mammals. If this view be ultimately maintained, it will be evident 



that the Cetacean order, as at present constituted, is a heterogeneous group ; while 



we should have a most remarkable instance of the power of adaptation to a 



particular mode of life of producing similarity in form. 



The Whalebone Whales. 

 Family BAL.ZXID^. 



The whalebone, or true whales, constitute but a single family, and are 

 characterised as follows. They have no teeth after birth ; but the palate is 

 furnished with numerous horny plates of baleen or whalebone, which serve to 

 strain the small animals on which these whales feed from the water, the structure 

 of this being explained below. The skull is symmetrical : and the two branches 

 nf the lower jaw are outwardly curved, and are joined at the chin only by fibrous 

 tissue. The nostrils open externally by two distinct longitudinal apertures. In the 

 skeleton the ribs are but very loosely united with the backbone, articulating only 

 with the horizontal transverse processes of the vertebrae, and having no connection 

 with the bodies of the same. The breast-bone is composed of but a single piece, 

 to which only one pair of ribs articulate 



As remarked by Sir W. H. Flower, in the substitution of baleen for teeth, as 

 well as in the loose connection of the ribs with the backbone and the breastbone, 

 and in the reduction in the size of the latter, the whalebone whales are more 



