THE SIFAKAS. 97 



The characters which distinguish this genus from Avahis and 

 Indris are the following : The fur with which they are covered 

 is more silky than woolly, and in general appearance is white, 

 more or less washed with yellow, varying to red or black. 

 The head is very slightly longer than it is broad, with a 

 black and almost naked muzzle ; the ears, half buried in the 

 fur, are flatter and wider than in Indris, the inner surface 

 being naked and black, and the outer haired. The nostrils 

 are large and semilunar in shape. The tail is long. The 

 index-finger is not united by a membrane to the others ; their 

 hands and feet are in a much less degree organs of prehension 

 than in most of the other Lemurs. 



The skull in proportionate length is intermediate between 

 that of Avahis and Indris. Compared with Avahis it is less 

 vaulted, its muzzle is longer, and the orbits are smaller. The 

 space between the eyes is high, and not depressed, on account 

 of the presence of a large air-cavity in the underlying bone. 

 Their nasal bones do not reach as far forward in front as the 

 level of the incisor teeth. In the dentition of the upper jaw, 

 the incisors protrude somewhat in front, and are dilated 

 laterally in a regular series thus distinguishing the genus 

 Propithecus from Lemur, the inner incisors being larger than 

 the outer ones, with their tips approximating. Between the 

 canine and the anterior pre-molar there is a short gap. 

 The anterior and median molars have the cusps of the crown 

 alternate ; the posterior has them opposite. In the lower 

 jaw the incisors are shorter and stronger than in Avahis, and 

 the molars are four cusped. 



The genus Propithecus contains three species; (T) The 

 Diademed Sifaka (P. diadema), (2) Verreaux's Sifaka (P. 

 3 v. i H 



