2ryO 



ANATOMY OF VERTEBRATES. 



in the size, shape, position, and direction of the innermost 

 digit, that it can be opposed, as a thumb, to the other digits, 

 thus constitutinor what is termed a ' hand.' Those Uno;uiculates 

 which have both fore and hind limbs so modified, or at least 

 the hind limbs, figs. 176, 180, form the order Quadrumana. 

 The incisors are commonly 2^, and the molars ^, broad and 

 tuberculate; they have perfect clavicles, an os penis, pectoral 



176 



177 



PelTic limb, Ape. 



Dentition of Woolly Lemur. 



mammre, vesicular and prostatic glands, a simple or slightly bifid 

 uterus, and a discoid, sometimes double, placenta. The Quadru- 

 mana have a well-marked threefold geographical as well as 

 structural division. The Strepsirhines are those with curved or 

 twisted terminal nostrils, with much-modified incisors, commonly 

 1^ ; premolars ~, Lichanotus, fig. 177, or ^^ in number, and 



178 



179 



Platyrhine dentition (Celus). 



Catarhiue dentition {Fupio). 



molars with sharp tubercles ; the second digit of the hind limb 

 has a claw. This group includes the Galagos, Pottos, Loris, 

 Aye- Ayes, Indris, and the true Lemurs ; the three latter genera 

 being restricted to Madagascar, whence the group diverges in one 



