100 



cells of the optic ganglia. Small particles of coagulated haemolymph also 

 extend down the outside of the eye for about half of its length. 



(July a very few specimeiis of the youii,g shrimp, P. antrorum, could 

 be obtained. These were from o to 5.5 mm. long. The optic stalli and eye 

 are much larger in proportion to the size of specimen (Fig. Ill) than in 

 the adult antrorum, but they are actually not as large as in the adult. 

 The internal structure showed no greater differentiation than in the eye 

 of adult. 



I am very grateful to G. H. Parker for assistance in the interpretation 

 of tlie structure of this eye. 



EXPLANATION OF FIGURES. 



Figure 1. Dorsal view of the front end of P. exilipes. 



Figure 2. Dorsal view of the front end of P. antrorum, showing the small 



eyes. 

 Figure 3. Dorsal view of the front end of a yoimg P. antrorum about 5 



mm. long. 

 Figure 4. I'liotograph of a cross section through the optic stalk of P. 



antrorum, showing the group of retinal hypodermal cells of 



the right eye. 

 Figure 5. Photograph of a longitudinal section through the optic stalk 



of P. antrorum. showing the group of retinal hypodermal 



cells. 

 Figure <;. Enlarged view (photograph) of group of retinal hypodermal cells 



shown in Fig. 5. 

 Figure 7. Photograph of another group of retinal hypodermal cells. Hor- 

 izontal section. 



BIBLIOGRAPHY. 



Benedict, James B., '00.— Preliminary description of a new genus and three 

 new species of crustaceans from an artesian well at San Marcos, Texas. 

 Proc. i:. S. Nat. Mus. Advance sheet. April 14, 1896. 

 Proceedings xviii. pp. 015-017. August 12, 1890. 

 Chilton, Charles, '94.— The Subterranean Crustacea of New Zealand; with 

 some general remarks on the fauna of caves and wells. 

 Trans. Linn. Soc. Loud., vi. pt. 2, 1894. 



