54 ANATOMY AND PHYSIOLOGY 



structure of its eyes is such a remarkable deviation 

 from every other living creature, that we hope to 

 be pardoned for the prolixity of these remarks. 



In the first place, the cornea presents an acute 

 horizontal angle, along its middle, and on each 

 side, sloping off at angles of forty-five degrees, the 

 corneas, for in reality there are two of them, are flat 

 surfaces, in our specimens, though probably slight- 

 ly convexed in life. Thus, it will be understood, 

 that two sides of a common prism, represents them. 

 On a careful dissection we have ascertained that 

 the sclerotica is a cartilaginous box, nearly globu- 

 lar, rolling within a bony orbit, which is entirely 

 elevated above the plane of the cranium. The 

 partition between the two corneas, is membranous, 

 and like the blade of a knife, the further edge be- 

 ing attached to the capsule of the crystalline lens. 

 The iris, therefore, is divided in the middle, so that 

 the pupil resembles a half moon, either side, or in 

 other words, above and below the horizontal parti- 

 tion. On minute inspection, we cannot discover 

 any difference of shape or structure in the lens, 

 from the same refracting instrument in the eyes of 

 other fishes. Certain it is, that the anableps can 

 perceive objects from above and below, embra- 

 cing half a circle in the sphere of distinct vision, 

 and that is the only advantage, at first view, we can 

 imagine they derive from the organization of the 



