Ml C RO SCO PICA L 



•Es8 A VS. 



s: The appearances which have been defcribed may be fecn on 

 the external fur face of the (hell with the naked eye ; but in order 

 to proceed to a further inveftigation of the fubjeft, the cornea 

 mull be removed from the {hell, and applied to a fingle micro- 

 fcope with a very ftrong light. 



" The internal furface of the large eyes, examined with; the 

 microfcope, is found to be thick fet with a great number of fmall 

 Iran fp are nt cones, of an amber colour, the bafes of which Hand 

 downwards, and their points upwards next the eye of the ob- 

 ferver. The cones in general have an oblique direction, except 

 fome in the middle of the cornea, about thirty in number, the 

 direction of which is perpendicular. 



"The center of every cone being the moft tranfparent part, and 

 that through which the light pafles, on that account the perpen- 

 dicular or central cones always appear beautifully illuminated at 

 their points. In a word, they are all fo difpofed, as that a cer- 

 tain number of them receive the light from whatever point it may 

 iflue, and tranfmit it to the immediate organ of fight, which we 

 may reafonably fuppofe is placed underneath them ; the cones are 

 not all of the fame length ; thofe on the edges of the cornea are 

 the longed, from whence they gradually diminifh as they ap- 

 proach the center, where they are not above half the length of 

 thofe on the edges." 



Of 



