2i6 ANDREWS. 



EXPLANATION OF PLATE IX. 

 [All figures drawn with camera and lenses of Zeiss.] 



Fig. I. Side view of anterior end of male Nereis alacris V., heteronereis state, 

 showing position of eyes. Proboscis protruding. X 50. 



Fig. 2. Part of section of eye of the same, showing union of rods (r) and coagu- 

 lated lens (/). X 700. 



Fig. 3. Section of outer part of eye of Nereis virens, showing approximation of 

 lens to cuticle. On right the lens is shrunken away from the rods. X 325. 



Fig. 4. Retinal cell with rod, Nereis limbata, epitoke state. Macerated in sea- 

 water and H2SO4. X 425. 



Fig. 5. Dorsal view of anterior end of a young N. limbata, 6 mm. long, x 50. 



Fig. 6. Isolated retinal cell and rod of Nereis pelagica. X looo. 



Fig. 7. Isolated retinal cell and rod, with fragments of lens, N. limbata^ epitoke 

 state. Haller's liquid, x 425. 



Fig. 8. Entire section through centre of posterior eye of N. alacris, heteronereis 

 state. X 325. 



Fig. 9. Isolated retinal cells and rods of N. alacris, heteronereis state. Hertwig's 

 liquid, followed by Haller's. x 700. 



Fig. 10. Isolated lens of the same. X 175. 



Fig. II. Side view of anterior end of N. limbata, epitoke. Proboscis extruded. 

 X 20. 



Fig. 12. Isolated rods of the same, side and end views. X 700. 



Fig. 13. Portion of section of an eye of N. pelagica, showing a process of the 

 cuticle approaching the lens, x 175. 



Fig. 14. Two retinal cells and rods of N. alacris, heteronereis state. The one 

 on the left vacuolated, probably by macerating liquid. X 1000. 



