124 ALLEN’S NATURALIST’S LIBRARY. 
ponderous Gorilla and the genus //omo. In external characters 
the Monkeys and Apes have in generala shorter and less Dog- 
like nose than the Lemurs, thin lips and a more distinct face ; 
while their eyes, situated on the face, are invariably: directed 
forwards, and never outwards, or to the side. The opening of 
their nostrils is either outward (as in those inhabiting the New 
World), or downwards (as in the bulk of the Old World 
species). All of them are covered with hair; the tail may be 
long, short, or wanting. The proportions of the fore-limbs 
to the hind- vary much in the different groups. The great 
toe, as well as the thumb, is (except in a few species) fully 
opposable, so that in the majority of members of the Sub- 
order, the foot is as good a prehensile organ as the hand. 
From this circumstance comes the designation, Quadrumana, 
or “‘four-handed,” so often applied to these animals. Ina few 
species the thumb is rudimentary or absent, but the fore- 
finger, the absence of which characterised some of the Lemurs, 
is always present and well developed, and the corresponding 
digit in the foot (except in the Marmosets) has a flat nail 
instead of a claw. The mamme of the Axthropoidea are 
always situated on the breast. If we examine the structures 
underlying the skin, we find that in the skull the orbits are 
entirely shut in by a bony wall, so that the finger cannot be 
passed into the temporal depression behind, as could be done 
in the Lemurine skull, and that the lachrymal foramen opens 
within the cavity for the eye. In the present Sub-order there 
is no toothless space in the mid-line of the upper jaw, the 
incisor teeth being set close together ; but there is always a 
vacuity, except in Man, between the incisors and the canine 
tooth. The lower canine teeth do not reseinble in form the 
incisors, nor do they protrude horizontally, as in the Lemurs. 
