the Genera of Hapalidee. 251 
In Cdipomidas edipus the hand is to all intents and 
purposes like that of Hapale jacchus. But in Leontocebus 
rosalia it is very different. Both the digits and the palm are 
exceedingly long. The pollex is set higher up, so that, when 
closed against the second digit, its tip falls considerably short 
of the distal end of the first phalanx of the digit. The third 
and fourth digits are closely tied together by a very narrow 
web nearly up to the distal end of the first phalanx, and a 
similar but wider and shallower web ties the third to the 
second digit. The fourth and fifth, on the other hand, are 
separated as in Callithrix and Cdipomidas. The palm is 
very long behind the plantar pad, its width across that pad 
being less than one-third of its total length. Finally, the 
second digit is considerably longer than the fifth, the two 
being subequal in Hapale jacchus and Uidipomidas edipus. 
The feet in the three species are very much alike, though 
varying in length, the elongation affecting the area behind 
‘the point of insertion of the hallux. The digits are separated 
practically down to the plantar pad, so that from the plantar 
aspect a very shallow web shows beyond the anterior edge of 
the pad. The hallux, inserted well behind the second digit, 
reaches when stretched forward approximately the posterior 
border of the plantar pad. As regards the length of the foot, 
in Hapale jacchus the sole is about three times as long as its 
width across the plantar pad. In Cdipomidas adipus and 
Leontocebus rosalia the corresponding comparative dimensions 
are respectively three and a half and four times. Thus, 
Leontocebus rosalia has a very long foot as compared with 
Hapale jacchus, and Gidipomidas edipus, in that particular, 
holds a position midway between them *. 
In connection with the feet, I am not able to point out any 
characters that can be used in the classification of marmozets. 
The hand, on the contrary, furnishes a good basis for the 
diagnosis of J. rosalia; and, since an examination of dried 
skins of this family in the British Museum and in the 
Zoological Society’s Collection shows that chrysomelas is the 
only species with hands like those of rosalia, these two 
species may be placed in a genus apart from other marmozets. 
The elongation of the feet in L. rosalia implies leaping 
powers surpassing those of Hapale jacchus, and it seems 
probable that the elongation of the palm and fingers of the 
hand and the tying together of the second, third, and fourth 
* The foot of Mystax midas seems to resemble that of CG. cedipus in 
length (Boas, Zool, Anz, xxxiv. p. 537, fig. 14, 1909). 
Li* 
