THE MAMMOTH CAVE. 99 



place by a prolongation forward of the external 

 membrane of the globe ; fifth, the globe was in- 

 vested by loose areolar tissue, which adhered to 

 it very generally, and in some instances con- 

 tained yellow fatty matter, — in one specimen it 

 formed a round spot, visible through the skin, 

 on each side of the head, which had all the 

 appearance of a small eye, — its true nature was 

 determined by the microscope only. It is not 

 improbable that the appearance just referred to 

 may have misled Dr. Dekay, where he states 

 that the eye exists of the usual size, but covered 

 by the skin. 



" If the superficial membrane above noticed 

 is denominated correctly the sclerotic, then the 

 pigment-layer may be regarded as the repre- 

 sentative of the clioroid. The form as well as 

 the position of the transparent nucleated cells 

 within the choroid correspond, for the most 

 part, with the retina. All of the parts just 

 enumerated are such as are ordinarily devel- 

 oped from and in connection with the enceph- 

 alon, and are not in any way dependent upon 

 the skin. But if the lenticular-shaped body is 

 the true representative of the crystalline lens, 

 it becomes difficult to account for its presence in 

 Amblyopsis according to the generally-recog- 



