Classification of Animals. 559 
composed of three minor circles, each of these in addition possesses 
distinctions of its own. The analogies of the Vertebrata to the pri- 
mary divisions of the Animal Kingdom are then glanced at, and 
they appear to stand thus. 
Mammalia, Vertebrata, 
Aves, ' -- - ; ''*''' Annulosa, 
Pisces, - ."- Radiata, 
Amphibia, Acrita, 
Reptilia, Mollusca testacea. 
The characters he selects for the arrangement of the Mammalia, 
in their primary circles, are the feet and the teeth, as being parts rea- 
dily seen and easily understood, and as having a direct influence upon 
their peculiar economy ; the first being remarkable as the organ of 
motion, the latter as indicating the nature and quality of the food 
upon which they subsist. We cannot, however, agree with Mr 
Swainson in thinking, that the internal structure and comparative 
anatomy of animals belong more properly to the province of the 
physiologist than that of the naturalist, for although external cha- 
racters alone may in general be suificient for the purpose of indi- 
cating natural groups, we consider them to be so intimately connect- 
ed with internal peculiarities of organism, that to understand and 
appreciate the value of the one requires the study and knowledge of 
the others ; in fact, that no one is entitled to the name of a natura- 
list, who limits his observations and researches to the mere external 
aspect of the beings with which he is engaged. 
The primary types of the Mammalia he considers to be, 1st, The 
Quadrumana, denned as possessing the three sorts of teeth, viz. in- 
cisors, canines, and molars ; the extremities of the four limbs per- 
forming the office of hands, one of the toes being opposible to the 
others, and acting as the thumb. 2d, Ferce, also with the three 
sorts of teeth, but the canines very large, the thumb or fifth toe 
placed on the same plane with the others, the claws often retrac- 
tile. The aberrant group, or the three aberrant circles, as they 
have not yet been proved to constitute a circle within themselves, 
are distinguished by their imperfect and variable dentition the un- 
der jaw being generally without the canine teeth. These groups are 
known by the names of the Ungulata, Glires, and Cetacece. The 
analogies of the orders of the Mammalia to those of the class Aves, 
are considered to stand thus, 
Quadrumana, - Insessores, 
Ferae, - - Raptores, 
