66 4 



COLLEGE ZOOLOGY 



there is no vermiform appendix. The principal groups are the 

 howlers, sakis, squirrel monkeys, and spider monkeys. 



The howling monkeys (genus Alonatta) 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 

 A teles, 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 



Fig. 530. — The black-handed spider have hind limbs about as 

 monkey, Ateles melanochir. (From Flower i .1 r v -u 



and Lydekker.) lon g aS the fore llmbs - 



They usually possess a long 

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

 thick patches of callous skin on which they rest when 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 nearl) 

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

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



