QUADRUMANA. 599 



hind-feet become, prehensile hands. The pollex (innennost 

 toe of the fore-limbs) may be wanting, but when present, it 

 also is usually opposable to the other digits, so that the animal 

 becomes truly quadrumanous, or four-handed. 



The incisor teeth generally are ?^^, and the molars ^H^, 

 • . , , 2—2 3—3' 



with broad and tuberculate crowns. Perfect clavicles are pre- 

 sent. The teats are two in number, and are pectoral in posi- 

 tion, and the placenta is discoidal and deciduate. 



' Fig 234 — Green Monkey or Guenon (^Cercocebiis sahaus) — after Cuvier, 



The Quadrumana are divided by Owen into three very 

 natural groups, separated from one another by their anatomical 

 characters and by their geographical distribution as follows : — 



Section A. Strepsirhina. — The , members of this section are- 

 characterised by the nostrils being curved or twisted, whilst 

 the second digit of the hind-limb has a claw. This section 

 includes the true Lemurs and a number of allied forms. It is 

 chiefly referable to Madagascar as its geographical centre ; but 

 it spreads westwards into Africa, and eastwards into the Indian' 

 Archipelago. 

 . Section B. Platyrhina. — This , section includes those Quad- 

 rumana in which the nostrils are placed far apart ; the thumbs 



