OSSEOUS SYSTEM OF MAMMALIA. 33 



partly by the frontal bone, partly by the superior maxillary, and partly 

 by the malar also by the lachrymal, and partly by the sphenoid and 

 ethmoid, and a process of the palate bone. The frontal bone forms the 

 upper margin of the orbit ; and a reflected plate, termed the orbital pro- 

 cess, concave below, forms the roof of the recess within : the floor and in- 

 ternal margin are formed by the superior maxillary bone ; the outer mar- 

 gin and side are formed, first, by the malar bone ; and, more internally, by a 

 portion of the wing of the sphenoid ; the inner wall is formed by the la- 

 chrymal bone, and a plate of the ethmoid : the orbitar plate of the palate 

 bone is seated at the bottom of the orbit. 



The recess, thus walled around, is (in Man) of a conical figure, with 

 various foramina and fissures for the transmission of the optic nerve, and of 

 the various nerves to the muscles of the eye, and to the face. At the inner 

 angle of each orbit is a canal in the lachrymal bone, for the transmission 

 of the tears, and leading into the nares : this lachrymal bone, which is small 

 in Man, and altogether within the orbit, is much more developed in many 

 quadrupeds, advancing externally, and encroaching upon the superior 

 maxillary bone. This is seen, to a remarkable extent, in the Horse. 



It is here to be observed, that the funnel-shaped orbits in the human 

 skull have an anterior aspect, and are nearly parallel to each other, ex- 

 cepting that they slightly diverge as they proceed from within, so that 

 the base, or external margin, of each is thrown somewhat obliquely out- 

 ward ; a peculiarity which, in the lower Mammalia, is carried much farther. 

 In the Monkey tribes, the direction of the orbits, and their form, are 

 nearly as in Man ; the margin, however, of the frontal bone projects 

 more decidedly, so as to constitute, in many, a bold superciliary ridge, 

 the forehead being at the same time depressed to its level. In other 

 Mammalia, however, as the Hare, the Deer, the Horse, &c., the orbits 

 are, more or less, lateral, so that the eyes, instead of seeing only such 

 objects as are in front, have a wide sphere of vision, comprehending 

 at least three parts of the horizon, or of a circle drawn around. The 

 design of Nature in this arrangement is very evident: the animals 

 whose eyes are most completely lateral, are those whose food is placed 

 under them, and whose structure unfits them for a life of rapine : 

 quiet and timid, they have not, with eyes intent upon their victim, to 

 keep up a persevering chase, nor have they, by the concentrated fierce- 

 ness of their look, to paralyze the awe-struck victim, and render it an 

 easy prey ; on the contrary, they themselves are the sufferers : ordained 

 by Nature's law to become the food of the carnivorous, without weapons 

 of resistance, or active defence, they have to maintain a continual watch. 

 Hence, in order to preserve the race from extinction, one mode, at least, 

 by which the design of Nature is accomplished, and it is one of passive 

 defence, results from the wide scope permitted to their organs of vision, 



