Page:The Fauna of British India, including Ceylon and Burma (Mammalia).djvu/39

Order PRIMATES.

This Order comprises Man, Monkeys, and Lemurs, aud therefore includes the most highly organized Mammalia. At the same time the Lemurs and some of the Monkeys are 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 are distinct. There are usually 5 unguiculate digits to both the manus aud pes, but the pollex may be rudimentary 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 incisors not divided by a space in the middle ....................................................................................................................................................................................................................................................

Anthropoidea.

B.

Orbit opening behind into temporal fossa beneath the postorbital arch. Pollex long, second digit with a long claw. Upper incisors (except in Chiromys) divided by a space in the middle ....................................................................................................................................................................................................................................................

Lemuroidea.

Suborder ANTHROPOIDEA.

A.

Premolars 2/2, molars 3/3; thumb, if present, opposable; internasal septum narrow. (Catarrhini.)

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 ....................................................................................................................................................................................................................................................

Hominidæ.