E. W. BERGER ON THE CUBOMEDUSZ. 45 
serve as a protection to the prisms of the vitreous portion of the 
retina during the adjusting movements of thelens. (But more on this 
below.) To my knowledge all previous observers are quite agreed 
on the structure of the capsule. Carriere and Haake, however, 
missed it altogether. 
Retina.—While I have enumerated (following previous observers) 
the vitreous body and the so-called retina as distinct parts, yet, as 
the sequel will show, they are, histologically, different parts of the 
same thing—namely the sensorium proper of the eye—and I propose 
to use the term retina for both taken together, while I retain the 
expression vitreous body (as hitherto used) for the vitreous portion 
of the retina. This simplifies matters; and using a word that is 
already used for analogous structures of other eyes (vertebrates, 
anthropods, molluscs) is conducive to clearness. I have been tempted, 
furthermore, to use the words rods and cones for the prisms and 
pyramids that I find in the vitreous bodies of the retinas of the complex 
eyes. But since the prisms in reality approximate prisms and the 
pyramids pyramids, in their shape, I have decided to retain the 
words prism and pyramid for these structures. The former of these 
terms (prism) was first used by Conant in his description of the 
complex eyes. 
What I shall call the retina, then, in the distal and proximal 
complex eyes of Charybdea, consists of three kinds of elements: 
the prism cells, the pyramid cells, and the long pigment cells. (Figs. 
4, 7, 22, pre, pyre, lp.) We may also describe the retina as com- 
posed of three zones: the vitreous zone (vitreous body of authors), 
the pigmented zone, and the nuclear zone. (Figs. 4, 7, 22, vb, pz, nz.) 
The cells composing the retina form a single layer in the shape 
of a hollow cup, into which cup the lens with its capsule fits. (Fig. 7.) 
This single layer of cells takes in the thickness of the vitreous zone, 
the pigmented zone, and the nuclear zone. Indeed, the distinctions 
vitreous zone (vitreous body), pigmented zone, and nuclear zone 
characterize three topographical regions of the retinal cells. 
That the retina is made up of three kinds of cells is most 
readily demonstrated in transverse sections through the vitreous 
body. Fig. 1 is such a section, taken quite near the pigmented 
zone (at about the level x, Fig. 4). Three different kinds of areas 
are readily made out in such a section. The more numerous areas 
