III 
CLASSIFICATION 
first great biological division is into kingdoms, namely, 
the animal kingdom and the vegetable kingdom. Then by 
classification the vast number of existing animals and plants are 
grouped so as to give each individual a definite place. By this 
system a beautiful order is established, which enables the student 
to find any particular animal or plant he may wish to study, and 
also to know its general characteristics from the name of the 
group to which it belongs. 
In broad generalization, objects of wide dissimilarity are rec- 
ognized as belonging to the same kingdom, as do trees and 
grasses, or as do birds and fishes. Certain trees or grasses and 
certain birds or fishes have such points of resemblance that they 
plainly show that they belong to subdivisions. The most untu- 
tored people recognize these distinctions, but the naturalist goes 
further and finds points of distinction which the casual observer 
overlooks. 
The animal kingdom has a varying number of divisions, called 
branches, subkingdoms, or phyla. Some late authors have admitted 
twelve divisions, and have given them the name phyla. Each 
phylum is composed of a group of animals with a plan of struc- 
ture which is common to themselves, but differs from that of the 
animals of all other phyla. 
The higher animals begin with the twelfth phylum, namely, 
the Chordata, or vertebrates. These animals have a spinal 
column, or series of vertebre, while the lower animals, or inver- 
tebrates are without a spinal column, and depend for stability 
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