172 PHILOSOPHY OF ZOOLOGY. 



thigh their peculiar enlargement and form. If the foot is 

 not adapted for laying hold of objects, neither is the hand 

 fitted for walking. It is placed in the same direction as 

 the arm, and is incapable of remaining in a horizontal posi- 

 tion, suited for supporting the body on the ground. It is, 

 however, well adapted for laying hold of objects by the 

 length of the thumb and fingers, and the facility with which 

 these oppose each other in the act of grasping. These in- 

 dications of the erect posture of man are common to all 

 the varieties of the race. The advantages attending this 

 position may readily be comprehended, by an examination 

 of his intellectual and instinctive powers. 



QUADRUMANA. 



The four extremities are formed for grasping. For this 

 purpose, the thumb on the feet, as well as the hands, is ca- 

 pable of acting in opposition to the toes. Both feet and 

 hands are placed nearly in the direction of the members to 

 which they are attached. Neither of them, however, are 

 fitted for walking, but both are suited for grasping. The 

 manner of life corresponds with this arrangement. The 

 species live in woods, and are accustomed to climb. 



Simiadce. 



Four approximate incisors in each jaw. 



The animals of this group have the transparent point on 

 the retina, as in Man. In the Lemuridae, a slight fold of 

 the retina may be observed, but it is destitute of spot or 

 transparent point *. 



BLUMENBACH, in reference to this point, observes, " As I have dis- 

 covered this central aperture in the eye of no animal besides Man, except 

 the yuadrumana, the axes of whose eyes are, like the human, parallel to 

 each other, I think its use connected with this parallel direction of the eyes. 

 As, on the one hand, this direction of the eyes renders one object visible to 

 both at the same time, and, therefore, more clearly visible ; so, on the other, 



