5r>6 MKMULKW UK T11K NATIONAL ACADEMY OF SCIENCES. 



1'l.ATK LIT. 



FIGS. 1S8. ISO. Parts of trans verso serial sections through the embryo of Pnhrmonetes vulgnris, at 

 the stage when pigment is just appearing in the eyes. In tlie anterior section (Fin- 

 1S8) the retiuogen is <i unicellular layer. x305. 



FIGS. 100-101. Parts of serial transverse sections through the brain, the. optic ganglia, and eye of 

 an embryo of Alpheus lirti'.rorhelix. In the anterior section (Fig. 100) the clusters of 

 cells which represent the ommatidia are well shown. Numerous ganglion colls are 

 dividing. x305. 



FIG. 192. Part of transverse section through eye, optic ganglion, and brain at a later stage. x-'505. 



RKFKUKNMK LKTTKKS. 



J. /, lirst :iiit.c.iin:i. 



All., alidoincn. 



CO., iT.v.stallino cone cells. 



im/., intercepting nwiiilininr. 



me*., ineaoderm. 



Het., retina. 



rtJ. [ , milinuMitii.rv i-ifj'nth proximal ivtinnlur cell. 



mil)., brain. 



2'., telson. 



-V., .stratum of large ganglion cells. 



1, :i, 1, proximal, external middle, and ilislal segments of optic ganglion. 



