Order PRIMATES. 



This Order comprises Mau, Monlveys, aud Lemurs, aud there- 

 fore includes the most highly organized Mammalia. At the same 

 time the Lemurs and some of the Monkeys ax'e of comparatively 

 low grade, and much inferior, at all events in development of brain, 

 to Mammalia belonging to other orders. 



The dentition throughout the order is heterodont (comprising 

 incisors, canines, premolars, and molars) and diphyodont. There is 

 a bony ring to the orbit, the clavicles are well developed, and the 

 radius and ulna ai*e distinct. There are usually 5 unguiculate 

 digits to both the manus aud pes, but the pollex may be rudi- 

 mentary or wanting. Either the pollex (thumb) or hallux (great 

 toe) or both are opposable. 



The members of this division are almost without exception 

 arboreal. 



The Primates are divided into two suborders. Many naturalists 

 class the Lemurs as a distinct order, for reasons that will be noticed 

 under Lemuroidea. 



The suborders are thus distinguished : — 



A. Orbit completely enclosed by bone behind. 



Pollex (or thumb) short (wanting in a few 

 instances) ; second digit of foot with a nail 

 similar to those of other digits. Upper in- 

 cisors not divided by a space in the middle . . Antheopoidea. 



B. Orbit opening behind into temporal fossa be- 



neath the postorbital arch. Pollex long, 

 second digit with a long claw. Upper in- 

 cisors (except in Cliiromys) divided by a 

 space in the middle Lemukoidea. 



Suborder ANTHROPOIBEA. 



2 3 



A. Premolars 5, molars 3 ; thumb, if present, 

 opposable ; internasal septum narrow. ( Ca- 

 tarrhini.) 

 I. No tail ; stature erect ; great toe or hallux 

 parallel with other toes, not opposable ; 

 arm shorter than leg ; no interval be- 

 tween upper canines and incisors ; 



canines not longer than incisors Hominidae. 



b2 



