MAMMALIA. 



359 



in clinging that it serves the purpose of a fifth hand (Fig. 

 378). The red-faced spider-monkey (Ateles) is one of the 

 most remarkable for the attenuation of its form. The tail 

 is extremely long and bare upon its under surface, and 

 with it they swing from limb to limb with the greatest ease. 

 In walking upright, the arms are often held high in air, 

 and the long tail curled over the head. The horned 

 monkeys (Cebus), the bearded saki (Pithecia), and the 

 howling monkeys (Mycetes), are familiar forms. The voice 

 of the latter is so powerful that it can be heard a mile, the 

 hyoid apparatus and windpipe (larynx) being wonderfully 

 modified into a sound-producer, the body of the former 

 assuming the functions of a large bony drum or air-sac 

 connecting with the larynx. In the male these curious 

 vocal organs are one third larger than in the female. Fol- 

 lowing are the Cercopithecida^ a group of monkeys peculiar 

 to the Old World. The face of the dog-faced apes is pro- 

 duced into a dog-like snout, more or less blunt or truncat- 

 ed ; the eyes are small, deeply set, and placed close to- 

 gether. The wanderoo (Macacus), the Gibraltar monkey 

 (Macacus t'nuus), the mandrill and chacma, and the bab- 

 boon (Cynocephalus], are familiar forms. Allied are the 

 Sleepers (Semn0pithecida) y of Africa and Asia. 



Apes (Simiidai). The animals of this family in their 

 physical development show a near approach to the human 

 type. Their position is nearly erect, the tail absent, and 

 the arms are much longer than the legs. The gibbons 

 (Fig. 379) (ffylobates) attain a length of three feet. In the 

 siamang, when standing erect, the fingers drag upon the 

 ground, the limbs being used to swing them through the 

 trees ; the thumbs and great toes only have nails. In color 

 they are black, the hair being long, coarse, and glossy. 

 They live in troops in the forests of Java, Borneo, etc., 

 and are generally led by a chief, who gives warning at the 

 approach of danger. The females show great solicitude 

 tor their young, and when in danger give vent to loud cries 



