266 CLASS MAMMALIA. 



traits which distinguish the species, are frequently so deli- 

 cate and evanescent that it is scarcely possible to study 

 zoology with complete effect, but in the midst of a mena- 

 gerie. There alone can we trace the successive modifica- 

 tions exhibited by the animal in the different stages of 

 infancy, adolescence, maturity and decline. There alone 

 can we assemble for the purpose of comparison, species, 

 which though similar, are yet distinct, and which nature 

 has not unfrequently located in almost opposite regions of 

 the earth. United in the same enclosure, their slightest 

 varieties become apparent, and the judicious observer has 

 at once the opportunity of enriching science with new 

 materials, and imparting to her disquisitions more pre- 

 ciseness and exactitude. 



It would seem, that the Green Monkeys with long and 

 arched tails, and the other general characters which we 

 have noticed in the two preceding kinds, constitute more 

 species in the Guenon subdivision than have yet been 

 enumerated by naturalists. They admit, however, but of 

 two. 



The Callitrix of which we have already spoken, and the 

 Malbrouc, on which we will now hazard a few observations. 

 This animal is one of the largest of the Guenon tribe. 

 Prom muzzle to tail it is about a foot and a half in length. 

 In walking on the earth he always supports himself on his 

 four hands — but as he is essentially organized for the pur- 

 poses of climbing and living in trees, his movements on the 

 ground possess neither- firmness nor facility. His hinder 

 limbs being longer than the fore, the motion of the anterior 

 part of his body cannot correspond to that of the posterior, 

 the latter proceeding with the greater rapidity. This 

 obliges him to carry the hinder part sometimes to the right, 

 and sometimes to the left, when he intends a slow motion, 

 and to shoot forward by jumps when he is desirous to run. 

 This conformation, so unfavourable for animals designed to 



