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, - MoUusca 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 

 Swair.son 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 sufficient 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 en gaged. 



The primary types of the Mammalia he considers to be, 1st, The 

 Quadrumana, defined 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, Ferat, 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 Ungulala, Glires, and Cetacean. The 

 analogies of the orders of the Mammalia to those of the class Aves, 

 are considered to stand thus, — 



Quadrumana, - Insessores, 

 Ferae, - - Raptores, 



