20O 



APES, MONKEYS, AND' LEMURS 



hand) is always furnished with a sharp claw. All lemurs have a well-developed 

 thumb and great toe ; but, curiously enough, in some of them the index finger of 

 the hand is rudimentary. They may or may not have tails, but these are never 

 prehensile, although, as in some of the marmosets, they maybe marked by alternate 

 dark and light rings. 



A point of resemblance to the monkeys and apes is shown by the number of 

 incisors, or front teeth, being very frequently two on each side of both jaws, in 

 place of the three which are so commonly present in other Mammals. In the apes 

 and monkeys, however, the central pair of incisors in the upper jaw are in contact 



SKELETON OF SQUIRREL-MONKEY (l), OF MUNGOOSE LEMUR (2), AND OF SLENDER LORIS (3). 



with one another, while in the lemurs they are almost invariably separated by a gap 

 in the middle line. This affords a ready means of distinguishing the skull of a 

 lemur at a single glance from the skulls of almost all other Mammals except bats 

 and some of the Insectivores. The lower front, or incisor, teeth of the lemurs 

 shelve forward, after the manner we have already mentioned as characteristic of 

 one group of the American monkeys (p. 172). 



Many lemurs are purely nocturnal animals, and it was probably from this cir- 

 cumstance, coupled with their silent habits and stealthy movements, that Linnaeus 

 was induced to give them the name by which they are now universally known. It 



