XIII PHYLUM CHORDATA 487 



Family ii. — Cebidce. 



Anthropoidea with the poUex not opposable, all the digits pro- 

 vided with flat nails ; without cheek-pouches or ischial callosities ; 

 with a broad nasal septum, and without bony external auditory 

 meatus. The tail is sometimes prehensile. The dental formula 



isi.-,c.-,p.-,m.-=36. 



This family includes the Howling Monkeys (Mycetes), Tee-Tees 

 (Gallithrix), Squirrel Monkeys {Chrysothrix), Spider-Monkeys 

 (Ateles), and Capuchin Monkeys (Gebus). 



Family iii. — Oercopithecidce. 



Anthropoidea with the pollex, when present, opposable ; with or 



without cheek-pouches ; with ischial callosities ; with a narrow 



nasal septum, and a bony external auditory meatus. The tail is 



not prehensile. The sternum is narrow. The dental formula 



• ■2123 



isi. -, c. -, p. -,m.- =32. The caecum is devoid of vermiform 



appendage. 



This family includes the Baboons {Gynocephahis) and Macaques 

 {Macacus). 



Family iv. — Simiidce. 



Anthropoidea with the pollex opposable ; without cheek-pouches ; 

 usually without ischial callosities ; with a narrow nasal septum, and 

 a bony external auditory meatus. The pectoral limbs arc much 

 longer than the pelvic. The caecum has a vermiform appendage. 

 The centrale of the carpus is sometimes absent. The dental 

 formula is the same as that of the preceding family. 



This family includes the Gibbons {Hylobates), Orangs (Simia), 

 Chimpanzees (Anthropopithecus), and Gorillas ( Gorilla). 



Family v. — Hominidce. 



Anthropoidea which differ from the Simiidse mainly in the more 

 perfect assumption of the erect posture, co-ordinated with altera- 

 tion of the curvature of the spine, and with the more complete 

 adaptation of the hind-limbs to bearing the weight of the body ; 

 in the absence of the power of opposition in the hallux, and its more 

 complete development in the pollex ; in the greater length of the 

 hind as compared with the fore-limbs ; in the smaller size of 

 the canine teeth; and the much greater size and complexity of 

 the brain. 



This family includes only the Human Species {Homo sapiens).- 



