the Genera of 'Ksi])A\id?e. 251 



III (Edipomidas cedipus the hand is to all intents and 

 purposes like that of Hapale jaccJius. Bat in Leontocehas 

 rosulia it is very different. Both the digits and the pahn are 

 exceedingly long. The pollex is set higher up, so that, when 

 closed against the second digit, its tip falls considerably sliort 

 of the distal end of the first phalanx of the digit. Tlie 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. Tlie fourth and fifth, on the other hand, are 

 separated as in GaUithrix and Qlldlpomidas. The palm is 

 very long behind the plantar pad^ its width across that pad 

 being less than one-third of its total length. Finall}^, the 

 second digit is considerably longer than the fifth, the two 

 being subequal in Ilapale jacchus and (Edipomidas oedlpus. 



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 appi-oxiinately the posterior 

 border of the plantar pad. As regards the length of the foot, 

 in Hapale jacckus the sole is about three times as long as its 

 width across the plantar pad. In (Edipomidas cedipus and 

 Leoiitocehus 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 jaccJius, and (Edipomidas cedipus, 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 L. rosalia ; and, since an examination of dried 

 skins of this family in the British Museum and in the 

 Zoological Society's Collection shows that chri/somelas is the 

 only species with hands like those of roscdia, 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 miclas seems to resemble that of CE. cedipus in 

 length (Boas, Zool. Anz. xxxiv. p. 537, fig. 14, 1909). 



17* 



