LEMURIDSE 683 



situated externally to the margin of the orbit (Fig. 327). The 

 pollex and hallux are always well developed, the latter being 

 especially large ; the second or index digit of the manus may be 

 rudimentary ; while in the pes the second digit invariably termin- 

 ates in a long pointed claw. The cerebral hemispheres do not 

 completely overlap the cerebellum, and are but slightly convoluted. 

 The uterus is bicornuate. The placenta is non-deciduate, and either 

 diffused or bell shaped the whole of the chorion except the 

 cephalic pole being covered with villi ; and the allantois is of very 

 great size. There may be abdominal mammae. Except in Chiromys, 

 the first pair of upper incisors are separated in the middle line. 

 In marked contrast to the Anthropoidea, the middle or transverse 

 portion of the colon is almost always folded or convoluted on 

 itself. (See Fig. 324.) 



In subdividing the group for the purpose of a more detailed 

 description of the different animals of which it is composed it must 

 first be noted that there are two very aberrant forms, each repre- 

 sented by a single species the little Tarsius of the Indian archi- 

 pelago, and the singular Chiromys or Aye-aye, which, though an 

 inhabitant of Madagascar, the headquarters of the suborder, and living 

 in the same forests and under the same external conditions as the 

 most typical Lemurs, exhibits a most remarkable specialisation in 

 the structure of its limbs and teeth, the latter being modified so as 

 to resemble, at least superficially, those of the Kodents, in which 

 order it was once placed. The differences between these two forms 

 and the remaining Lemurs are so great that the whole suborder 

 naturally divides itself into three families, the first of which may 

 be again divided into four subfamilies. 



Family LEMURID^E. 



Upper incisors two on each side, small and separated by an 

 interval in the middle line. Upper canine large, conical, com- 

 pressed, and pointed. Premolars two or three, molars three on 

 each side above and below, with numerous more or less pointed 

 cusps. In the front of the lower jaw are on each side two or three 

 closely approximated, long, slender teeth lying almost horizontally 

 and projecting forwards. These are generally considered to repre- 

 sent the incisors and canine, but there is some doubt about their 

 homologies, and they may be all considered as incisors, the canine 

 being absent. The first lower premolar larger than those behind 

 it, and shaped like a canine, of which it performs the function 

 (Fig. 327). The orbit and temporal fossa widely continuous beneath 

 the bar of bone (formed by the frontal and jugal) constituting the 

 posterior boundary of the former cavity. The fibula well developed 

 and distinct from the tibia. All the digits of both feet (except the 



