INTBODUCTION. 
Zoology is that branch of Natural History which treats of animals, 
and embraces not only their structure and functions, their habits, in- 
stincts, and utility, but their names and systematic arrangement. 
Various systems have been proposed by different naturalists for the 
scientific arrangement of the animal kingdom, but that of Cuvier, with 
some modifications, is now thought the best, and a sketch of it will be 
found under the head of the Modern System in this Introduction. As, 
however, the System of Linnaeus was formerly in general use, and is 
still often referred to, it has been thought advisable to give a sketch of 
it first ; that the reader may be aware of the difference between the 
old system and the new one. 
L1NNMAN SYSTEM. 
According to the system of Linnaeus, the objects comprehended within 
the animal kingdom were divided into six classes : Mammalia or Mam- 
miferous Animals, Birds, Amphibia or Amphibious Animals, Fishes. 
Insects, and Worms, which were thus distinguished : 
Classes. 
{u^ t>i^j (Viviparous I. Mammalia. 
Hot Bl00d 1 Oviparous II. Birds. 
n m a tu™h i With lungs III. Amphibia. 
Cold red Blood .{ Wlthgill3 b IV. Fishks. 
sai I t.t.., L , n u u- t t>i a (Having antenna;.. V. Insects. 
I Withoutvertebr*. .Cold white Blood { Havin » tentliCnl& yj WoRMg 
OEDEES OF MAMMALIA. 
The first class, or Mammalia, consists of such animals as produce 
living offspring, and nourish their young ones with milk supplied 
from their own bodies ; and it comprises both the quadrupeds and the 
Jtacea. 
This class was divided by Linnaeus into seven Orders : viz. primates, 
tta, ferce, gltresy pecora, belluce, and ceiacea (this order was called 
}ete by Linnaeus) or whales. The characteristics of these were 
founded, for the most part, on the number and arrangement of the 
