PLATE IX. 



Structure of the Eye. 



Fig. 1. Surface view of membrane limiting the " ommateum" below ; a, perforations for 

 the nerve fibres arranged in groups of four, corresponding to each retinula ; 

 V, nuclei. 



Fig. 2. Scmidiagrammatic .section through the eye of Serolis schytkei ; c, corneal lenses ; 

 ■11, nuclei of Semper ; v, vitreous body ; r, retinula cells ; ^j, pigmentiferous 

 connective tissue corpuscles ; h, hyaline cells ; s, rhalxlom. 



Fig. 3. Single element of the eye of Serolis cornuta, depigmented and isolated by 

 teasing; r, rhabdom ; /, its posterior filiform prolongation; h, hyaline cells; 

 n, their nuclei. 



Fig. 4. Single element of the eye of Scrolls cornuta to show the pigment sheath sur- 

 rounding the rhabdom [r). 



Fig. 5. Single element of the eye of Serolis schytkei ; r, rhabdom ; h, hyaline cell. 



Fig. 6. One of the hyaline cells ; n, its nucleus. 



Figs. 7, 8. Transverse section through the upper part of the retinula of Serolis schythti; 

 r, rhabdom ; 2^, pigment. 



Figs. 9-15. A series of figures to show the varying form of the rhabdom in Seivlis 

 cormtta. 



Figs. IG, 17. Transverse section through the upper part of tlie retinula of Serolis 

 cornuta ; r, rhabdom ; j?, its pigment sheath. 



Figs. 18, 19. Two isolated retinula cells of Serolis schythei ; r, rhabdomcre. 



Fig. 20. Series of transverse sections through retinula of Serolis schythei; a, nervous 

 rods below meml)rane ; h, lower end of retinula cell just above the pigmented 

 membrane ; c, retinula cells at the level of the nucleus (n) ; (/, four retinula 

 cells surrounding the hyaline cell (h) ; e, upper extremity of the retinula cells ; 

 (if), rlial)domere. 



