The general plan of the development of the organ in Calotes versicolor in no way differs from that of Sphenodon and Lacerta. The lens of the parietal eye of Calotes appears at a comparatively later state of development than in Sphenodon and Lacerta. The papaphysis in the embryos of Calotes versicolor is a simple structure. Histologically all the structures resemble the wall of the brain from which they arose.