252 Mr. R. I. Pocock on 



fingers are cliaracters functionally correlated with the increased 

 activity, and serve the purpose of givinj^ at the same time 

 a longer span and a safer grip on a branch when the animal 

 alights from a long-distajice spring. 



It might be held that the small hallux and the claw-tipped 

 digits of the Hapalidre are primitive features derived direct 

 from an unguicuiate arboreal ancestor, probably of a lemuroid 

 type, but preceding in those particulars modern lemurs, which 

 have a hallux of great length and thickness and digits tipped 

 with flat or flatfish nails ^. But, in my opinion, the Hapalidfe 

 may be best regarded as derived from the typical Platyrrhine 

 monkeys, from which they have departed in the numerical 

 reduction of the teeth and in the appendicular particulars 

 above-mentioned. The only Platyrrhine Primate outside tiie 

 limits of the Hapalldse which has the hallux small and the 

 digits claw-tipped, as in tiie marmozets, is CalUmico, Thos. ; 

 and it is to be remembered that both in CalUmico and the 

 Hapalidae these characteristics of the hands and feet are 

 associated with smaliness in size and lightness in build. 

 These little monkeys, indeed, are the most diminutive of all 

 the true Primates, and, owing to the small size and narrow 

 transverse span of the hands and feet, they are unable to 

 gr;isp branches of any width. Nevertheless, since they are 

 extraordinarily active and jump with great power, they require 

 special means of maintaining a hold on the branches they 

 traverse or alight on. In this need may be found, I think, 

 the modification of the nails into claws and the concomitant 

 reduction of the hallux which, while depriving the hands and 

 feet of the peculiar prehensile capacity seen in other Primates, 

 have converted them into extremities resembling functionally 

 those of squirrels in their power of hooking on to the rough- 

 nesses of baik, of thick brandies, and tree-trunks. 



The Ears. — In Hapale jacc/ncs the ears are large, with the 

 upper edge, wdiich is folded, either evenly rounded or sub- 

 angular posteriorly, and the posterior border, which is 

 unfolded, also evenly and widely rounded and forming infe- 

 riorly a continuously expanded lamina to a point just below 

 the large fleshy valvular antitragus. The flap of the pinna 

 extends widely beyond the central cavit}- of the ear both 

 above, behind, and below, and its inferior portion just behind 

 the antitragus shows a marked depression following the curve 



* With tlie exception, of course, of the second digit of the foot, which 

 in every genus carries a claw, and also of all the digits, apart from the 

 haWu:^, oi Daitbento)iia {Chu-07)ii/s), in which the nails have been con- 

 verted into claws. 



