2i8 ANDREWS. 



EXPLANATION OF PLATE X. 



[Figures drawn with Zeiss camera and lenses.] 



Fig. 15. Tangential sections of retina oi Nereis alacris, heteronereis state. Partly 

 depigmented in Grenacher's liquid. a, at level of clear axial passages ; b, just 

 peripheral to a. x 930. 



Fig. 16. Section like a of Fig. 15, but entirely depigmented in eau de Javelle. 



Tangential section as in 15, a, but not depigmented. X 930. 

 Tangential section peripheral to Fig. 17. Not depigmented. X 930. 

 Tangential section nearer periphery of retina, cutting nuclei. Not depig- 

 X 930- 

 20. Isolated retinal cell and rod of young TV. limbata, 6 mm. long. X 930. 

 Fig. 21. Section of entire eye of same, x 430. 



Fig 22. Radial section, part of retina of N. alacris, heteronereis state. Partly 

 depigmented in eau de Javelle. X 930. 



Fig. 23. Same as last, but entirely depigmented in Grenacher's liquid, x 930. 

 Fig. 24. Tangential section across bases of rods near retinal pigment. N. alacris, 

 heteronereis state, x 930. 



Fig. 25. Same as last, showing boundaries of rods as well as granular axes. X 930. 

 Fig. 26. Tangential section across rods near the lens. X 930. 

 Fig. 27. Tangential section of part of lens when shrunk into polygonal, rod-like 

 masses. X 930. 



Fig. 28. Asterope Candida Clpd. Radial section through retina and all of the 

 refracting media of the eye. i, optic nerve fibres; 2, retinal cells; 3, pigment zone; 

 4, retinal rods; 5, granular material at ends of rods; 6, zone of coarsely reticulated 

 coagulum; 7, granular line of demarcation; 8, zone of finely reticulated coagulum; 

 9, granular line of demarcation at pheriphery of lens proper, 10. x 230. 



Fig. 29. Amphinome Pallasii ? Section of young eyes in regenerated head. Case 

 of duplication of a posterior eye. X 230. 



Fig. 30. Section of entire eye. Same as Fig. 29. x 560. 

 Fig. 31. Section of entire eye of Eulalia annulata ? x 560. 



