92 ALLEN'S NATURALIST'S LIBRARY. 



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 Indrisince is very long, the 

 caecum, 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 rete 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. 



