FIRST GREAT DIVISION OF THE ANIMAL KINGDOM. 
THE VERTEBRATE ANIMALS. 
The bodies and limbs of these being supported by a 
frame-work composed of connected pieces moveable 
upon each other, they have the more precision and 
vigour in their movements : the solidity of this support 
permits of their attaining considerable size, and it is 
among them that the largest animals are found. 
Their more concentrated nervous system, and the 
greater volume of its central portions, impart more 
energy and more stability to their sentiments, whence 
result superior intelhgence and perfectibility. 
Their body always consists of a head, trunk, and 
members. 
The head is formed by the cranium, which incloses 
the brain, and by the face, which is composed of the 
two jaws and the receptacles of the organs of sense. 
Their trunk is supported by the spine of the back 
and the ribs. 
The spine is composed of vertebrae moveable upon 
each other, of which the first supports the head, and 
which have an annular perforation, forming together a 
canal, wherein is lodged that medullary production 
from which the nerves arise, and which is called the 
spinal marrow. 
The spine, most commonly, is continued into a tail, 
extending beyond the hinder limbs. 
The ribs are semicircles, which protect the sides of the cavity of the trunk : they 
are articulated at one extremity to the vertebrae, and are ordinarily attached in front to 
the breast-bone ; but sometimes they only partly encircle the trunk, and there are 
genera in which they are hardly visible. 
There are never more than two pairs of limbs ; but sometimes one or the other is 
wanting, or even both : their forms vary according to the movements which they have to 
execute. The anterior limbs may be organized as hands, feet, wings, or fins ; the 
posterior as feet, or instruments for swimming. 
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