664 



COLLEGE ZOOLOGY 



there is no vermiform appendix. The principal groups are the 

 howlers, sakis; squirrel monkeys, and spider monkeys. 



The howling monkeys (genus Alouatta) range from South 

 America to Mexico. They possess a resonating apparatus, with 

 which they increase the power of the howls they are in the habit 

 of emitting, probably for the purpose of frightening away ene- 

 mies. The sakis (genus Pithecia) inhabit northern South Amer- 

 ica; they have long, bushy tails which are non-prehensile. The 

 squirrel monkeys (genus Chrysothrix) are very active species in- 

 habiting central and north- 

 ern South America. The 

 spider monkeys (genus 

 Ateles, Fig. 530) are 

 slender, long-limbed forms 

 ranging northward into 

 southern Mexico. They 

 possess a very prehensile 

 tail, but the thumb is 

 lacking. 



The Old World monkeys 

 (CERCOPITHECID^E) are 

 mostly quadrupedal, and 

 have hind limbs about as 

 long as the fore limbs. 

 They usually possess a long 

 tail, which is never prehensile; their buttocks are provided with 

 thick patches of callous skin on which they rest v/hen in a sitting 

 posture; their nostrils are separated by a narrow space; and 

 many of them have cheek-pouches. The Indian and African 

 monkeys belong to this family. Only one species, the Barbary 

 ape, enters Europe; this peculiar tailless form is found on the 

 Rock of Gibraltar. 



The anthropoid apes (SIMIID^E) are the primates most nearly 

 related to man. The tail is absent; the fore limbs are longer 

 than the legs; locomotion is often bipedal, and when walking the 



FIG. 530. The black-handed spider 

 monkey, Ateles melanochir. (From Flower 

 and Lydekker.). 



