HA2 CLASS MAMMALIA. 



their natural history, without seeking for characters better 

 defined, and more easy of detection, than those hitherto in 

 use, on which to establish the distinction of species. 



" But as the human faculties are too limited to make a si- 

 multaneous comparison of a great number of objects, as the 

 mind proceeds only by the way of generalization, and has 

 scarcely acquired any ideas, but it begins to unite them in 

 groups, and then again forms other groups more compre- 

 hensive, for the purpose of descending by degrees from 

 these general, to more particular subdivisions, we have 

 thought proper to begin by making in this immense fa- 

 mily of the monkeys a sufficient number of separations; that 

 they may not produce false ideas, that they may not unite 

 together very different species, or separate those which are 

 similar, it was necessary to seek the basis of such divisions 

 in the most important differences of conformation, in those 

 which are most intimately influential on the whole animal 

 system. 



" We could not employ the generic cases of preceding 

 zoologists, which are little less defective than their specific 

 characters. The tail, for instance, this member, or rather 

 this appendage, superfluous and foreign to the body, must 

 of necessity prove a very defective basis of distinction. In 

 point of fact, there is a Mandrill found without a tail. The 

 Magot, which has none, approximates closely to the Maca- 

 ques which have this organ. The case is similar with the 

 posterior callosities ; if we adopt them as an essential cha- 

 racter, the Guenon, which is named Douc {Simla nemceus, 

 Lin.) would come after the Orangs, and the Gibbon would 

 be removed from their vicinity. 



" The cheek-pouches, as organs accessary to nutrition, 

 are not without importance. They serve as the basis of a 

 division, which to be sure does not forcibly sunder kindred 

 genera, but which fails, however, of uniting them under 



