CARNARIA. 61 



and those in which they are bristled with points live principally on 

 Insects. The articulation of their lower jaw, being transversely 

 directed and hinge-like, allows of no lateral motion; it can only 

 open and shut. 



Although the convolutions of the brain are still tolerably well 

 marked, it has no third lobe, nor does it cover the cerebellum any 

 more than in the following families; the orbit is not separated from 

 the temporal fossa in the skeleton; the cranium is narrowed and the 

 zygomatic arches widened and raised, in order to give more strength 

 and volume to the muscles of their jaws. Their predominant sense 

 is that of smell, and their pituitary membrane is generally spread 

 over numerous bony laminae. The fore-arm has still the power of 

 revolving in nearly all of them, although with less facility than in 

 the Quadrumana, and they never have the thumb of the anterior 

 extremities opposed to the other toes. On account of the substan- 

 tial nature of the aliment, and to avoid the putrefaction it would 

 undergo by remaining too long in an elongated canal, their intes- 

 tines are less voluminous. 



There is a great variety in their forms and in the details of their 

 organization, which produces analogous differences in their habits, 

 and to such an extent as makes it impossible to arrange their ge- 

 nera on one line, and compels us to form them into several families, 

 which are variously connected by multiplied relations. 



FAMILY I. 



CHEIROPTERA. 



This family still retains some affinity with the Quadrumana. 

 Their distinguishing character consists in a fold of the skin, which, 

 commencing at the sides of the neck, extends between their four 

 feet and toes, supports them in the air, and even enables such of 

 them to fly as have their hands sufficiently developed for that pur- 

 pose. This disposition required strong clavicles and large scapula; 

 to give the necessary solidity to the shoulder, but it was incompati- 

 ble with the rotation of the fore-arm, which would have diminished 

 the force of the stroke requisite for flight. They have all four great 

 canini, but the number of their incisors varies. They have long 

 been divided into two genera, founded upon the extent of their or- 



