IN NATURAL HISTORY. a 
culture and science in his time — would not be 
the language of all cultivated men. He took, 
therefore, little pains to characterize the animals 
he alludes to, otherwise than by their current 
names; and of his descriptions of their habits 
and peculiarities, much is lost upon us from 
their local character and expression. There is 
also a total absence of systematic form, of any 
classification or framework to express the divis- 
ions of the animal kingdom into larger or lesser 
groups. His only divisions are genera and spe- 
cies: classes, orders, and families, as we under- 
stand them now, are quite foreign to the Greek 
conception of the animal kingdom. Fishes and 
birds, for instance, they considered as genera, 
and their different representatives as species. 
They grouped together quadrupeds also, in con- 
tradistinction to animals with legs and wings, 
and they distinguished those that bring forth 
living young from those that lay eggs. But 
though a system of Nature was not familiar 
even to their great philosopher, and Aristotle 
had not arrived at the idea of a classification on 
general principles, he yet stimulated a search 
into the closer affinities among animals by the 
differences he pointed out. He divided the ani- 
mal kingdom into two groups, which he called 
Enaima and Anaima, or animals with blood and 
animals without blood. We must remember, 
