THE PINEAL BODY 



125 



4. Lenticular and flattened, as in Anguis frcgilis, Lacerta 

 vivipara, Lacerta agilis, Lacerta viridis, Seps tridactylus, Varanus 

 giganteus, Plica, Iguana, and Calotes. 



5. Flattened so that the under wall is pressed inward, 

 as in Varanus bengalensis, Leiolaemus nitidus, and Calotes 

 ophiomachus. 



6. Flattened and decidedly elongated, as in Seps chalcidica 

 and Calotes versicolor. 



Fig. 64 The pineal eye of Anolis, according to Spencer, 1886 



While the dorsal wall of the parapineal vesicle forms the true 

 lens of the parietal eye, the ventral wall is pigmented and gives 

 rise to the retina. The latter consists of layers of different 

 types of cells. In the embryonic stages it is attached to the 

 brain by a tubular prolongation from the roof-plate. The first 

 detailed description of the parietal or third eye in reptiles was 

 given by deGraaf 155 in 1886. Spencer's 366 work appeared in 

 the same year, and a number of investigations have been reported 

 since then confirming in a general way the conclusions of these 



