160 FAMILY SIMIAD^. MONKEYS. 



tracts, if such should be in their neighbourhood. The callosities 

 enable them to take their repose in a sitting posture, and thus 

 render them more independent of a convenient place of rest than 

 are most of the Apes. We find some approach to them, how- 

 ever, in the Gibbons ; whose habits more resemble those of the 

 Monkeys, than do those of the higher Apes. And the tail serves 

 to them very much the same purpose as the pole to the rope- 

 dancer, acting as a balance to ensure their equilibrium, when 

 their hands are otherwise occupied, and guiding them like a rud- 

 der in their leaps through the air. In accordance with the prin- 

 ciples so often alluded to, we do not find that the characters which 

 distinguish the group of Monkeys are possessed by all the mem- 

 bers of it. Thus, in the genus Semnopithecus, we find the cheek- 

 pouches almost completely absent ; but this deficiency is compen- 

 sated by a very remarkable development of the stomach, which 

 has'several distinct pouches, or sacs, branching off as it were from 

 its principal cavity (Fig. 70). The thumb, too, is very short 



FIG. 70 THE STOMACH OF SKMNOPITHKCUS. 



and imperfect in these animals ; and in the genus Colobus it is 

 entirely absent. 



151. The first genus of Monkeys, that of Semnopithecus, 

 bears many points of resemblance to the Gibbons, besides the 

 absence of cheek-pouches in the one, and the presence of rudi- 



