THE PINEAL BODY 137 



thick retina. The latter is pigmented and contains rod cells. 

 The lens is bi-convex. What Spencer considered a nerve was in 

 all probability connective-tissue remains of a former nerve. A 

 narrow parietal foramen occurs while the cornea and parietal 

 spot are absent. 



3. Leiolcemus niiidus. Spencer ('86). 367 In this form the 

 epiphysis exists as a hollow, proximal part and a horizontal 

 solid end portion. The latter is stretched forward to reac the 

 parietal foramen. The parietal eye is dorsoventrally flattened 

 and has a narrow lumen. The upper surface of the retina is 

 flat and horizontal. The lens is present. There are rod cells 

 which are the chief elements in the retina. The lens is bi- 

 convex and the nuclei of the lens cells lie in a layer deeply 

 situated. There is a parietal foramen in which the eye is lodged. 

 The corium is clear. There is a light colored parietal spot. 



4. Leiolaemus tennis. Spencer ('86). 367 The epiphysis ex- 

 tends forward to a well-marked parietal eye. There is no con- 

 nection between the two. The parietal eye has a pigmented 

 retina and a lens. The parietal cornea and parietal spot are 

 present. 



5. Plica umbra. Spencer ('86). 367 The epiphysis has , a prox- 

 imal part and a horizontal portion which is solid and reaches the 

 parietal eye. The latter is connected with the epiphyseal end- 

 sac. The parietal eye is much flattened and the retina is pig- 

 mented. It is situated in a deep parietal foramen. The cornea 

 is present as well as the parietal spot. 



6. Iguana tuberculata. Spencer ('86) ; 367 Leydig ('96) ; 239 

 Klinckowstroem ('93). 207 In this form the epiphysis is well 

 developed with a large end-bud in connection with the proximal 

 portion. The latter has a more or less follicular appearance. 

 In embryos the cells have cilia, but these later disappear. Klinc- 

 kowstroem in the 18 mm. embryo describes a tractus pinealis in 

 the distal end of the epiphysis. A parietal nerve is described by 

 the same author in 1894. In embryonic stages it connects the 

 retina with the roof of the brain. The parietal eye is globular 

 and in some forms a highly differentiated retina is present. An 

 actual nerve layer appears only in the embryo and later disap- 



