828 THE POPULAR SCIENCE MONTHLY. 



One fine day a revolution was effected. Just as an adaptation 

 to arboreal life was produced at the expense of anterior species, 

 an adaptation to terrestrial life was made, with a bipedal attitude 

 favorable to a more extended vision, a diminution of the olfactory 

 sense and of the facial prominence, a more perfect touch, and in- 

 telligence. Henceforth, all the living forces of adaptation tended 

 toward the same end ; the hind-thumb ceased to be opposable, the 

 other toes diminished in length; what the feet lost the hands 

 gained, and man was created, exclusively bimanous in front, ex- 

 clusively bipedal behind, and all the accessory parts in the seg- 

 ments of the limbs confirming themselves in the types, less ac- 

 cented till now, which they had presented since the marsupials. 



The peculiarity set forth by Cuvier of the opposable thumb 

 perfectly characterizes what there is common and special among 

 all the apes, the faculty of clinging to trees with the four extrem- 

 ities. It is true that this expresses only one of the details of that 

 whole, perfect in man, which has given birth to the words hand 

 and foot, but it is the essential one. It can not, however, be denied 

 that the second characteristic necessary to the function of pre- 

 hension — great mobility in every direction of the segments of the 

 limb — is not very greatly developed in the hind-limbs of monkeys. 

 Cuvier had, then, a perfect right to call all the monkeys quadru- 

 mana, although they were at the same time quadrupedal, and to 

 oppose them to man. I, then, put the anthropoids and ordinary 

 monkeys together under the name of monkeys, and will not recoil 

 from the synonym of quadrumana if the term monkey does not 

 suffice me. 



The monkeys are divided into two groups, those of the old con- 

 tinent, also called catarrhinians, because their nostril-partitions 

 are narrow and their nostrils are open below the nose (from Kara, 

 low, and piv, nose) ; and those of the new continent, also called 

 platyrrhinians, because their nostril-partitions are broad, and 

 their nostrils open on the side (from TrXarv's, flat). The monkeys 

 of the new continent are predominantly tree-dwellers, and are 

 divided into two families — the monkeys proper of this continent, 

 and the arctopitheci. The former are in turn divided into the 

 diurnal — the howlers, the ateli, the sajous, etc. ; and the nocturnal, 

 including the sagoins, sakis, nyctipitheci, and the saimiris. 



The arctopitheci or hapales are a group apart among monkeys, 

 including the interesting wistit and the tamarin. They are tree- 

 dwellers like the former group, and nocturnal like the latter. 

 They afford an example of the imperfection of our modes of 

 classification. They are monkeys, American monkeys, in many 

 of their relations ; but they lack the single characteristic that dis- 

 tinguishes all the monkeys, including the lemurs, and have the 

 dentition neither of the American monkeys nor of the monkeys of 



