j^g ANDREWS. [Vol. VII. 



lobe of the lens, so as to barely cut it off from contact with the 

 thick cuticle. 



The pigment is exceedingly dark, the rods are very short. 

 In certain places the lens may shrink away from the rods, as on 

 the right of the figure, in such a way as to leave slender fila- 

 ments and drawn-out coagulated threads, as of a slimy material, 

 that correspond to the retinal rods in number and position, and 

 also are to be traced into the lens as lines. 



Such connections of lens and retinal rods were seen in the 

 epitoke A^. alacris also. 



Nereis pelagica Linne. 



In sections and macerations of the eyes of atoke individuals 

 we find here the same structure again. 



In surface views of an eye there is, however, a conspicuous 

 line corresponding to the major axis of the somewhat elliptical 

 pupil, but not as long as it, which seems to be the line of meet- 

 ing of the epidermal, corneal cells over the lens. This was 

 observed in N. viretis also, but not as plainly as in the present 

 case. In anterior eyes there are vacuole-like clear bodies along 

 this line and at one end, often, a clear ingrowth of the cuticle, 

 seen in sections (Fig. 13) to be a conical plug of cuticular 

 substance extending inward nearly to the lens. 



This Hnear structure seems to correspond to a bilateral 

 arrangement of the elements of the lens, sometimes indicated, 

 when these elements do not run out to the cornea, but bend in 

 toward a meridional plane. 



The whole appearance, as far as understood, indicates a con- 

 nection of lens and cuticle, and strongly suggests some sort of 

 invagination or sinking in from the surface. 



The retinal cells are often extremely long and slender, with 

 short rods (Fig. 6). Moreover, they are so crowded that very 

 slender ones amongst the less slender sort have their nuclei 

 in a conspicuous zone near the dense pigment, and thus the 

 retina appears as if made of two layers of cells. This is not, I 

 judge, actually the case, but due, as above stated, to the crowd- 

 ing of perfect and imperfect, or greatly attenuated, cells. 



In brief recapitulation, we may characterize the eye of the 

 Nereidae as a pigmented retinal cup, lined by clear rods, and 

 filled by a refracting substance of doubtful origin, the entire 



