HAPALID& CEBIDJZ. 787 



PLATYRRHINA. CATARRHINA, 



No sigmoid flexure in the colon A sigmoid flexure, 

 descendens. 



Never more than a slight The caecum is conical, with a 

 narrowing at the end of the vermiform appendix in Apes, 



caecum, which is usually bent 

 like a hook. 



No hints of a "secondary dis- A "secondary discoidal placenta" 

 coidal placenta." (only hinted at in" Anthropoid 



Apes). 



Family -i. HAPALID^E ( = Arctopithecini). Marmosets 



The marmosets are the smallest monkeys, not much 

 larger than squirrels. They live in companies in the 

 Neotropical forests, especially in Brazil, and feed on insects 

 and fruit. 



In addition to the general Platyrrhine characters, the 

 following are noteworthy. 



Their dentition, ^, is distinctive, for other Anthropoidea 

 have ? molars. The molars have three main tubercles 

 instead of the usual four. The pinna of the ear is very 

 hairy. The tail is long, bushy, and non-prehensile. The 

 pollex is long, but not opposable; all the digits have a 

 pointed claw except the short opposable hallux. The 

 cerebral hemispheres have few convolutions. The marmo- 

 sets often bear three young ones at a birth, whereas the 

 other monkeys usually bear but one. There are two 

 genera, Hapale and Midas. 



Family 2. CEBID/E. American Monkeys 



The American monkeys occur throughout tropical 

 America, but are most at home in Brazil. In addition to 

 the general Platyrrhine characters, the following are note- 

 worthy. The tail is long except in Brachyurus^ and is 

 often prehensile. The digits have nails, not claws; the 

 thumb if present is opposable. The pinnae are more or 

 less naked. The dentition is characteristic, for there are 

 six back teeth ; the formula being 2133. All are uniparous. 



