270 



FRANK H. PIKE. 



edge of the stalk slopes inward and backward to the rostrum. 

 The entire outline of the eye-stalk, when viewed from above, is 

 singularly free from the graceful curvature of the normal eye- 

 stalk. The same structures seen in the side view appear in this 

 view. The tip of the eye-stalk is directed outwards away from 

 the rostrum, and the optic nerve springs from the outer side of 

 the anterior end of the optic ganglion. The granules are applied 

 to the lateral surface of the stalk. The anterior end of the optic 

 ganglion is more rounded than it is in the side view. 



General Appearance in Sections. The specimen on which the 

 account of the minute anatomy here recorded is based, measured 

 17 mm. in length. The eye-stalk is 1,044 rnicra in its greatest 



length and 793 micra in its 

 greatest width. The ratio of 

 the length of the eye-stalk to 

 its width is 1.3. The cuticula 

 of the eye-stalk varies in thick- 

 ness. It is 14.3 micra thick on 

 the outer side of the stalk away 

 from the rostrum, 10.9 micra in 

 the region where the retinal 

 elements are applied to it, and 

 FIG. 3. Low power microphotograph 7-2 micra on the inner side of 



of eyes of blind shrimp from above, ct, the tip next the rostrum, 

 corneal cuticula ; <, retina ; a, fibrous por- 

 tion of optic ganglion ; o, cellular portion 



of optic ganglion ; //, hypodermis. 



In the left eye, the hypoder- 

 mis and the retina have adhered 

 to the tip of the stalk, but the 

 optic nerve has broken so that the retina and the optic ganglion 

 are separated. The retina is applied to the side of the eye- 

 stalk. In the right eye, the hypodermis and the retina have 

 pulled loose from the corneal cuticula, but the optic nerve is un- 

 broken. (Fig. 3.) 



The optic ganglion appears as a fibrous area surrounded by 

 small cells with large, deeply-staining nuclei. The hypodermis 

 has been torn loose from the sides of the eye-stalk and, in places, 

 lies close to the optic ganglion. Transverse sections of the eyes 

 of a specimen killed in Vom Rath's fluid show the hypodermis 

 lying in contact with the cuticular wall. 



