Iq6 ANDREWS. [Vol. VII. 



korper" of Graff, and a lens proper, or dense spheroidal mass 

 near the pupil. I find, however, no membrane separating 

 those two regions, nor any between the whole mass and the 

 retinal rods ; more granular parts of the coagulum represent 

 what have been described as membranes in other genera. 



Thus, in a radial section passing through the centre of the 

 lens, there are in Asterope the following regions, as shown in 

 Fig. 28 : — 



I. The expanded optic nerve on the periphery of the retina, 

 2. The single layer of elongated retinal cells. 3. The zone of 

 yellow-red pigment granules. 4. The layer of long retinal rods. 

 5. A granular zone comparable to the area of vacuoles seen in 

 Nereis (Fig. 2), between the rods and the lens. 6. A thick zone, 

 peripheral part of the " glaskorper," composed of reticulated 

 coagulum. 7. A sharp line of granules. 8. A very thick zone 

 of reticulations, closer than those in the peripheral part. 9. A 

 second granular line forming the boundary of the granular, hard, 

 refracting lens. 10. This is often broken into parallel pieces, 

 but presents a central, more dense part, with concentric struc- 

 ture. The lens proper (10) and the "glaskorper" (5-8) are 

 thus all one continuous mass of coagulum of varying density in 

 successive concentric zones. Both together may be called the 

 lens in the wide sense. 



The large eyes of the Alciopidae, so often studied, do not, 

 apparently, agree with those of the other families as elucidated 

 here. 



The chief differences lie in the closed state of the optic cup 

 and in the nature of the lens. The former character may prove 

 to be an erroneous conception derived from imperfect knowledge 

 of the difficult corneal region of the eye. The structure of the 

 lens as made out in Asterope shows at least its continuity with 

 the retina, and allowing for the important difference obtained 

 by various methods of preparation, we cannot deny that the 

 peripheral part at least, the "glaskorper," may be really com- 

 posed of separable, rod-like elements. In fact, Graber has 

 figured such elements in Alciope Contrainii, as well as their 

 contimdiy with the epidermis. Yet it would be unjust to accept 

 those results when denying the reality of the membranes and 

 supernumerary nuclei also figured there. 



