34 INTRODUCTION. 



which affords them timely notice of approaching danger. In these ani- 

 mals, the eyes are generally large, full, and protuberant. The eye of 

 the Giraffe, for example, is remarkable for its beauty. It is ample, and 

 beams with an expression of gentleness, in accordance with the creature's 

 character : one of the most striking circumstances connected with it is its 

 prominence ; and, so much so is this the case, that the eye-ball is per- 

 fectly apparent to any one standing in a right line behind the animal, 

 while the person, occupying such a position, is equally visible to the 

 Giraffe. A native of the hills and plains of Africa, abounding in fero- 

 cious beasts of prey, among which the Lion is its most formidable enemy, 

 the Giraffe takes in the horizon at a glance, almost without moving ; 

 and, thus enabled to discern an enemy at a considerable distance, he may 

 browse at ease on the foliage of the mimosa. 



The annexed sketch (fig. 1 7) represents a posterior view of the head 

 of this singular and interesting animal ; the lateral 

 position and prominence of the eyes are very con- 

 spicuous. 



The lateral, or semilateral aspect of the orbits, in 

 the lower Mammalia, tends to place the fundus, or 

 bottom, of one orbit in opposition to the fundus of the 

 other ; and this, the more completely, the more late- 

 ral their situation ; so that, instead of forming nearly 

 parallel conical cavities, as in Man and the Simiae, 

 they are so opposed, that a transverse line across the 

 frontal bone traverses each in its natural direction. 



Thus, While the margins are thrown apart, the orbits, at their fundus, more 

 or less approach each other ; the extent of the intervening space depending 

 on the posterior dilatation, and the general magnitude of the nasal cavity. 

 The distance between the eyes, or the margin of the orbits, varies, there- 

 fore, according to the breadth of the forehead, and the development of 

 the nasal organs, and is often very considerable, while yet the fundus of 

 each orbit, as in the Hare, may closely approximate. In the Horse, the 

 distance between the orbits, from margin to margin across the skull, 

 equals the distance of the occiput from a line drawn between them. 



Though the orbits are widely separated in the Carnivora, their axis 

 is much more obliquely anterior than in the Deer or Antelope ; therefore 

 the aspect of the eyes is far less lateral : in this respect, however, there 

 is great variation throughout the different genera. 



In many of the aquatic Mammalia, as the Beaver and Coipus, the 

 orbits, widely separated, have their axis directed obliquely upward, so that 

 the eyes appear as though placed almost on the upper surface of the skull 

 a situation advantageous to the animals while swimming, because it enables 

 them to look upward, without the necessity of turning the head. 



