PINEAL EYE IN LACERTILIA. 237 



Fig. 19. — Section through a part of the upper wall of the swollen extremity 

 of the epiphysis in Cyclodus. C. Cilia of cells bounding the cavity of the 

 epiphysis. Ant. (Le) The elongate cells, equivalent to those forming the 

 lens of the parietal eye in other forms, n. Oval nuclei of the cells. 



Fig. 20. — Section through portion of the under wall of the same. Post. {R.) 

 Ends of the cells facing into the cavity in the position of the rods of other 

 forms, n. Circular nuclei of the cells. 



Fig. 21. — Longitudinal vertical section through the parietal foramen of 

 Chameleo vulgaris, showing the optic vesicle, pineal stalk, and epiphysis. 

 The yellow sha^de indicates the parietal bone. 



PLATE XVII. 



Fig. 22. — Longitudinal vertical section through the parietal foramen and 

 pineal eye of Leiodera nitida. The great elongation of the cells of the 

 rete mucosum is drawn, and the entire absence of pigment from the cutis vera 

 above the eye indicated. 



Fig. 23. — Pineal eye of Iguana tuberculata, cut in section and re- 

 moved from the parietal foramen. When in position the optic axis looks 

 directly upwards. 



Fig. 24. — Longitudinal vertical section through the parietal foramen of 

 Anolis (sp. ?), showing the pineal eye lying within the vacuolate tissue, to- 

 gether with the pineal stalk. 



Fig. 25. — Longitudinal vertical section through the parietal foramen of 

 Anguis fragiiis, showing the pineal eye separated from the proximal portion 

 of the epiphysis and the forward extension of the latter. 



Fig. 26. — The eye of Lacerta viridis, viewed as a solid object lying 

 within the parietal foramen. 



PLATE XVni. 



Fig. 27. — The pineal eye of Lacerta o cell at a, viewed as a solid object 

 lying within the parietal foramen, one half of which has been cut away. The 

 eye lies within a mass of branched pigment cells, amongst which ramify the 

 branches of the blood-vessel which accompanies the pineal stalk. 



Fig. 28. — The brain of Lacerta ocellata, with the pineal eye lying in 

 the dura mater, viewed from the side. 



Fig. 29. — The brain of Cyclodus gigas, viewed from the side, with the 

 epiphysis stretching forwards and upwards and ending in a swollen part within 

 the parietal foramen surrounded by pigment. (The foramen should not be 

 closed above.) 



