LEMURIDA 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 mamme. 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 Rodents, 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 LEMURIDE. 
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 
