136 FREDERICK TILNEY AND LUTHER F. WARREN 



wall of which was definitely pigmented. McKay ('88) 255 found 

 a bi-convexed lens, a good retina with rod cells and round cells, 

 a molecular layer, and also a spindle-celled layer and peculiar, 

 triangular elements. The lumen was traversed by a fine strand. 



7. Moloch horridus. Spencer ('86). 367 In this species the 

 organ is strongly pigmented, more likely an end-vesicle with a 

 stalk than a parietal eye. The parietal foramen in which the 

 organ rests is present. Both cornea and parietal spot are 

 present. 



8. Agama caucasica. Owsiannikow ('88). 295 In this species 

 there is a relatively large parietal eye with rods in the retina, 

 which latter is otherwise well developed, There is also a lens, 

 a parietal foramen, a vitreous, cornea, and a parietal spot. In 

 one case, Ritter ('94) 333 found an accessory organ which he 

 called the parapineal organ. It was situated in the parietal 

 foramen somewhat to the left of the parietal eye. No corium 

 was above it. A common, connective tissue capsule contained 

 both organs. The accessory organ was larger than the parietal 

 eye. There was no lens or retina in the accessory organ. 



9. Phrynocephalus Vlangalii. Owsiannikow ('88). 295 In the 

 20 mm. embryo this species has a parietal eye. The organ is 

 deeply pigmented. 



IGUANIDAE. 1. Phrynosoma orbiculare. Studnicka ('93). 384 

 In this species the epiphysis is broad and globular and con- 

 nected by a stalk to the roof of the brain. It presents an end- 

 bud on its distal extremity. Ependymal cells in the body con- 

 tain a brown pigment. In the lumen there is a coagulum which 

 consists of a syncytium of pigment-containing cells. The pari- 

 etal nerve was not observed. The parietal eye is small, dorso- 

 ventrally flattened with a well-developed lens and retina. The 

 lens is bi-convex. The cells of the lens have their nuclei situated 

 near the under surface. The retina is filled with pigment, hid- 

 ing its main structure. The position of the parietal eye is in a 

 wide foramen, four times as large as the parietal eye itself. The 

 parietal cornea and spot are present. 



2. Anolis. Spencer ('86) , 367 This species presents a well-devel- 

 oped parietal eye which is ovoid in form and has a well-developed, 



