558 Classification of Animals. 
thing" walking upon legs, pronounces it, and justly, to be an insect ; 
and yet such is the wonderful and almost inconceivable variety that 
nature has lavished upon this class, that it is highly probable the 
aspect of an insect admits of half a million of variations, without such 
a departure from the great outlines of the original type, as would 
prevent any one variation from being confounded with a bird, a fish, 
or a quadruped." 
He afterwards passes to the consideration of the primary divisions 
of the animal kingdom, as proposed by MM. Cuvier, Lamarck, and 
Virey. Preferring that of the latter, as being most in consonance with 
nature, he therefore adopts the Vertebrala, the Annulosa, and the 
Mollusca, as the three primary circles of the animal kingdom, the 
two first forming the typical and subtypical groups, the latter the 
aberrant, composed of the three minor circles of the Mollusca testacea, 
Testaceous Mollusca, the Acrita or Polypes, and the Radiata or ra- 
diated mollusca. The peculiar characters of each division are also 
detailed, as well as the manner pointed out, in which they blend the 
one into the other, so as to constitute one great circle, composed of 
the Acrita, Mollusca, Vertebrata, Annulosa, and Radiata. 
The Mammalia, as being the most complicated in their organiza- 
tion, as well as the most perfect in their senses, he naturally places 
at the head of the vertebrata, and their more obvious characters 
are defined, as, Female suckling her young ; body covered with hair 
or fur ; possessing four legs ; warm blood ; and living upon the 
ground. Not one of these characters, however, is perfectly absolute, 
but, taken collectively, they are sufficient to discriminate a qua- 
druped from all other animals at present in existence. Birds (Aves) 
follow next in rank to quadrupeds, having an organization less com- 
plicated, and an inferior degree of intelligence. They are charac- 
terized by having only two legs, corresponding to the hinder pair in 
mammalia, the anterior being represented by the wings. The body 
is clothed with feathers, the blood warm, and the young are pro- 
duced from eggs hatched by the parent. 
The third great division, composed of the circles, Reptilia, Am- 
phibia, and Pisces, contains animals much inferior in organization 
and intelligence to the two former, and peculiarly distinguished by 
having cold blood, and a body either entirely naked, or covered with 
scales, besides the negative characters of neither suckling their 
young like quadrupeds, or flying in the air like birds. These are 
the characters possessed by the aberrant group as a whole, and 
which distinguish it from the quadrupeds and birds ; but as it is 
