PINEAL BYE IN LACERTTLIA. 199 



that of Chameleo than any other, there being no differentia- 

 tion of the walls to form a lens and retina. The shape of the 

 vesicle is, however, unlike that of Chameleo, being elongated 

 dorso-ventrally. Its walls consist of nucleated columnar cells, 

 and are thicker anteriorly than posteriorly, where there is 

 present a small amount of pigment on the external surface of 

 the cells. 



The whole structure lies in the parietal foramen, and has the 

 form, viewed as a solid object, of a small ovoid body whose 

 anterior end is closely apposed to the connective-tissue, forming 

 a roof to the parietal foramen, between which and the cuticle 

 no pigment is present. The pineal stalk is a prominent struc- 

 ture, entering the posterior end of the vesicle where it unites 

 with the cells ; unfortunately, in the specimen examined the 

 part with the optic vesicle and portion of the pineal stalk 

 attached to it was torn away from the underlying structures, 

 but their can be little doubt from the similarity between this 

 form and such as Chameleo, that the stalk simply passes back 

 to join the proximal portion of the epiphysis, the upper part of 

 which is seen running forward in the dura mater directly 

 towards the optic vesicle. 



Calotes, PI. XV, figs. 13 and 14; PI. XVIII, figs. 31 and 

 33; PI. XX, fig. 8. 



In smaller species of Calotes the external indication of 

 the eye is most clear. A large median scale is so modified 

 (fig. 13) as to present precisely the appearance of an eye. In 

 its centre is a circular black space, within which lies a white 

 ring enclosing a dark space resembling exactly the pupil. This 

 efi'ect is produced by reason of the central part of the scale 

 being transparent and slightly raised into a dome-shaped cornea, 

 while beneath it lies the pineal eye which, on removal of the 

 scale, is seen to have a globular form. The external surface is 

 covered with a glistening white substance, save anteriorly, where 

 the transparent lens is placed ; the internal cavity is lined by 

 the rods embedded in deep pigment, and hence appears in- 

 tensely dark when seen through the lens, the whole eye having 



