34 CLASS MAMMALIA. 



By the length of the nose and the convolute surface on 

 which the Schneidarian membrane is stretched, ruminants 

 are endowed with an acute sense of smelling, necessary for 

 the nice selection of their food, in the choice of which the 

 preference is so predisposed, that while nearly all the genera 

 and species will feed on the most common plants, each have 

 some particularly grateful or harmless to them, so that 

 scarce any exist that are not adapted to this special end of 

 subserviency to animated nature. Their ears are placed 

 far back and very moveable, the most advantageous position 

 for hearing behind the animal while feeding, because at 

 that moment it is most exposed to unseen danger, the at- 

 tention and eyes being engaged in a great measure before 

 it: the pupil of the eyes, in the whole order, is invariably 

 of an oblong form, enabling them to take a more extensive 

 horizontal range of vision without turning the head or lift- 

 ing it from their food. The eye is furnished with a nicti- 

 tating membrane stretching from the inner canthus to nearly 

 half over the ball, thus protecting those organs from dan- 

 ger while in search of their food. In common with 

 other quadrupeds, they possess a seventh muscle of the eye, 

 called suspensorius, fixed in the sclerotic coat, and intended 

 to sustain the weight of the orb, and to prevent the optic 

 nerve being stretched ; the posterior part of the cricoid 

 coat, called the tapetum, is, in them, generally of a green 

 passing into a blue colour, to enable them to see their food 

 the better, and facilitate vision in the dark. 



To the strength of their skulls, already noticed, are added in 

 most species, osseous prolongations from the forehead, form- 

 ing either sessile antlered horns, or bony cores, upon which 

 the horny covers vaginate and construct true horns : these 

 serve for defence, and for conquest among themselves in the 

 strife for females, it being intended by nature that the most 

 powerful should chiefly procreate the breed, and thus trans- 

 mit the character of the species in full vigour to posterity. 



