2 ALLEN’S NATURALIST’S LIBRARY. 
9 
side, the posterior tooth of the series having a hind inner cusp. 
The anterior and median molars are four-cusped, of which the 
outer and inner pairs are separated by a longitudinal groove ; 
to the outside they have one supernumerary cusp on each 
main cusp, and one between them. ‘The median molar is the 
largest tooth of the jaw, and the posterior is small, triangular 
and three-cusped. Of the lower jaw, the outer pair of the 
long, and almost horizontally protruding incisors, is larger 
than the inner pair, and is separated by a space from the 
anterior pre-molar. Of the elongate laterally compressed _pre- 
molars, the anterior is the larger, and is vertically taller than its 
fellows, being slightly depressed forward and curved behind ; 
the posterior pre-molar has one cusp. The molars have four 
cusps, of which the inner ones alternate with the outer cusps. 
The intestinal canal in the Jvdrisitne is very long, the 
ceecum, or blind diverticulum at the junction of its two por- 
tions, being extremely long and large, occupying, indeed, a 
great part of the abdominal cavity. ‘The main arteries of the 
fore- and hind-limbs do not break up into a ,zete mirabile, 
or series of small parallel vessels, as in many other Lemuroids. 
In this group, while the sense of smell is very perfect, that 
of hearing is less acute than in the other Sub-families ; and that 
of touch conspicuously blunt, both in the fingers and toes, 
which are chiefly climbing and not tactile and prehensile 
organs, as they are in the corresponding limbs of the Anthro- 
poids. ‘The female never produces more than one young at a 
birth. 
The convolutions of the brain are few, but they are more 
complicated than in many of the South American Monkeys. 
In very young individuals the cerebellum is more covered by 
the cerebrum than it is in the adult. 
