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 molluses 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 rule, 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 finner 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, 
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 many important respects, and if they are derived from 
a single stock, their common ancestor must have existed at a comparatively remote 
epoch. Dr. Kiikenthal 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. 
Habits. 
Classification. 
THE WHALEBONE WHALES. 
Family BALZNIDZ. 
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 
of 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 vertebre, 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 
