No. 2.] EYES OF POLYCH^TOUS ANNELIDS. 195 



In the Phyllodocidae, then, we fail to find any indication of a 

 composite nature in the lens, though it is connected with the 

 cuticle, and not sharply separated from the retinal rods. 



The detailed description of the very large eyes of Genetyllis 

 occulata M'Ini., given by M'Intosh (9), shows clearly that the 

 retinal cells are pigmented and bear rods, but does not clear up 

 the nature of the lens. The material obtained was, however, 

 one specimen that had been "slightly dried." 



Alciopid^. 



Asterope Candida Claparede. 



Through the courtesy of Professor Patten I have been able to 

 examine well-preserved material from Naples, but only in sec- 

 tions, thus leaving much unobserved. 



Owing to the great size and refractory nature of the lens, and 

 to its close approximation to the cuticle, no clear conception of 

 the nature of the cornea could be obtained. No connection of 

 lens and cuticle was discovered, the epidermis apparently contin- 

 uing all over the region of the pupil. Moreover, the retinal cup 

 itself seems to be closed by an inner cornea passing across the 

 pupil, and thus making two cell layers between the lens and the 

 cuticle, as has been described by Graff (l) and by Carri^re (3) 

 and denied by Graber (2). However, the material is insufficient 

 to decide this point, and from similar results in Nereis and other 

 annelids, I am inclined to think the optic cup here also may be 

 an open one when seen in true meridional sections. 



The retina, as one would judge from the majority of previous 

 observations, is undoubtedly a single layer of cells, each bearing 

 a clear rod, very easily studied. The pigment is restricted to a 

 sharply circumscribed zone where cell body and rod unite and 

 is, I judge, actually in the cells of the retina, not in any special 

 pigment cells, nor outside the retinal cells. Moreover, in my 

 section at least, there are no clear axial regions as in Nereis, 

 but on the contrary, the pigment is densest at the axis of each 

 cell, where the rod arises. This concentration of pigment may 

 account for the nucleus-like bodies observed here by some 

 authors. 



The very large refracting mass central to the layer of retinal 

 rods is clearly divisible into a peripheral coagulum, the " glas- 



