♦54 Opposable Paver of the 



t to the idea that 



. r. : :. -r ■: r r ■: < i . .-r r, ■".-■■= : 



cr.Cc possessed SS 



on the genera Mvcetes 



to the actions of the 



from time to time 



Surrey Zoological, Gardens, 



the other fingers in the act of 

 islanding the 

 by the backward position of 

 the organ, that they bad not the power of doing so: and, in fact, 

 power of prehension seems to be altogether 

 of the thumb; tor, generally speaking, it was not 

 ction at all, at least not simultaneously with the 

 but hong loosely on one side, as I hare seen it 

 do, in like circumstances, in the opossums, pbalangers, and 

 other ar bore al mammals. When actually brought into play, 

 however, the thumb of the Cebi invariably acts in the same 

 direction as the other fingers; and, consequently , the exception 

 might be supposed, on a casual exami- 

 to oner to the general law of organisation presented 

 by the other Smnadseofi the New World, is altogether illusory, 

 when put to the test of more accurate investi- 



1 hare not enjoyed the same oppor tuni ties of extensive 

 observation among the Callitrices: indeed, I hare seen only 

 two species of this genus alive: but their actions, as well as 

 the form and position of their anterior thumbs, were in all 

 respects similar to those of the Cebi ; nor hare I any reason 

 to believe that other American Suniada? diner in this respect 

 from those which I hare seen, and of which I have here 

 described die actions. 



It has been already observed that the genera Mycetes, La- 

 gothrix, Aotus, Pitbecia, and Hapale bare the anterior thumb 

 placed absolutely upon the same line with the other fingers, 

 and acting habitually in the same direction ; and I have now 

 shown that the backward position of this organ in the Cebi 

 and Callitrices is die only equivocal circumstance which ap- 

 pears to differentiate dnem from the other Sknhdse ; but that, 

 when observed more closely and in action, the deception 

 vanishes, and its functions are found to diner in no respect 

 from those of the allied genera. Here, then, we have obtained 



c 



and far more important character, by which to distin- 

 the Siuree of the Old and New Worlds, than those which 

 been hitherto so much insisted upon by zoologists, the 



