DEGENERATE EYES IN THE CUBAN CAVE SHRIMP. 269 



the tip, the part of the stalk below this line is slightly concave 

 for about one-half the distance from the tip to the base of the 

 cone. From this middle point of the base of the cone on to the 

 base of the stalk, the outline is again convex. 



The cuticula is clear white and partially transparent, with no 

 trace of facets in the corneal region. There may be seen through 

 it () a white mass, very nearly concentric in curvature with the 

 outline of the eye-stalk, extending from the base forward a little 

 more than two-thirds of the distance to the tip of the stalk, and 

 terminating in a blunt cone ; (/>) a find strand running from a 

 point a little below the end of this cone forward to (c) a small 

 group of granules in the tip of the stalk. These granules appear 

 to be spread over a small area on the proximal face of the cutic- 

 ular tip, and taper to a narrower diameter where the thread joins 

 them ; (V) a space appears between the white mass (<?) and the 

 cuticula on the sides of the stalk. No trace of pigment is visible 

 with any magnification. In sections these structures are seen to 

 to be (i) the optic ganglion, (2) the optic nerve, (3) the rem- 

 nants of the retina 

 and dioptric appa- 

 ratus, and (4) a 

 space filled with 

 haemolymph, re- 

 spectively. 



Any great amount 

 of shrinkage due to 

 reagents would cer- 

 tainly break the 

 fine strand of fibers 



runnilio" to the ran- ^ IG ' 2 ' Eye-stalk viewed from above. ;, rostrum ; e, 

 _ eye-stalk ; a optic ganglion ; b, optic nerve ; f, retina ; </, 



ules in the tip. I space filled with hsemolymph . 

 am inclined, there- 

 fore, to believe that the greater part of the space seen between 

 the optic ganglion and the cuticula is normal in this eye. 



II. Viewed from above, the outer side of the eye-stalk slopes 

 inward toward the rostrum at an angle of I 5 to 20 degrees to 

 the longitudinal axis of the body. (Fig. 2.) The stalk termi- 

 nates in a blunt, slightly rounded cone. The anterior mesial 



