No. 2.] EYES OF POLYCH^TOUS ANNELIDS. 185 



From the above it appears that the eye in the Eunicidae is 

 fundamentally like that in the Nereidae. The retina, however, 

 has some attenuated cells which bear imperfect rods or slender 

 ends passing into the lens. The lens shows no sign of being 

 made of elements corresponding to the retinal cells, but is more 

 like a secreted mass. It is, however, connected with the cuticle, 

 is a part of the cuticle, and not separable from the cuticle, 

 though when this is invaginated a short distance, it may appear 

 as a secretion morphologically external to the cuticle. 



The continuity of lens and cuticle, as well as the existence of 

 the retinal rods, was recognized by Graber (1) in Ewiice vittata 

 and E. Harassii. His account of the retina and rods is, how- 

 ever, quite different from that given above in the presence of a 

 definite membrane separating these two zones and the interpre- 

 tation of small bodies in the adjacent ends of rods and pigment 

 cells as being two zones of nuclei. 



I do not regard the membrane-like line found in my material 

 as a true membrane, and have not seen the nuclei. 



Pruvot (4) describes and figures the eye of Hyalinoecia tiibi- 

 cola as a spheroidal mass of two concentric zones of elongated 

 cells all buried in and not separated from the brain. These 

 cells have swollen, nucleated ends towards the brain, and then 

 extend as slender processes or bodies to the lens, from which 

 they are not separated by any line whatever, but rather pene- 

 trate into it. This lens is, moreover, merely a small rounded 

 inward growth or process of the cuticle. The pigment appeared 

 to be between the bodies of the cells ; the eye figured is that of 

 an albino. 



The eyes of Eimice torqtiata are said to have the same struc- 

 ture. These, however, as well as the eyes of E. Harassii have 

 been most excellently figured by Jourdan (5). This author finds 

 no separation of retina and rods in the species in which Graber 

 figures so evident a membrane, but recognizes the fact that 

 each rod is but the clear end of a retinal cell. All the retinal 

 cells are pigmented and end in rods. 



The nuclei nearest the pigment end of the cells he regards 

 as their true nuclei, while the more peripheral ones are in a 

 peculiar zone of anastomosing ganglion cells continuous with 

 the pigmented retinal cells. (Some of my preparations incline 

 one to suppose this may be the true state of the case, though 

 another interpretation has been preferred.) 



