PINEAL EYE IN LACERTILIA. 197 



or with the rods. Their flattened bases rest upon the connec- 

 tive-tissue investment of the eye. 



At its posterior extremity enters the pineal stalk. The 

 appearance of this in one form examined is given in fig. 23, 

 where it had the form of a simple nervous strand, much as in 

 Hatteria, the specialised rods running down into it, though 

 there was no group of nucleated bodies to be seen at their 

 external ends. 



Draco volans. 



The eye is present in Draco volans, though the specimens 

 examined did not make it possible to investigate the structure in 

 detail, the vesicle walls having apparently shrunk and come to 

 lie close together, so as to obliterate the internal cavity. The 

 whole is in a condition, as far as could be ascertained, which 

 resembles that seen in Chameleo or Lyriocephalus. 



The vesicle is ovoid in shape, and placed with its long axis 

 in the median line of the head within the parietal foramen ; its 

 walls are composed of cells with very distinct nuclei, but no 

 further differentiation to form retina or lens could be distin- 

 guished, and the vesicle itself was remarkable for the absence 

 of pigment in its walls, a feature already noticed in Chameleo 

 and Lyriocephalus. The only pigment present lay in the 

 dura mater, and surrounded the very posterior extremity of 

 the vesicle in the position in which the pineal stalk would 

 enter, though it was not possible to determine the existence of 

 this. 



Externally specimens of Draco differed somewhat in their 

 indication of the organ, its position being in most cases easily 

 determined by the presence of a specially modified scale in the 

 usual position, and bearing a cornea-like space. 



Ceratophora aspera. 

 The organ is indicated externally in the usual manner by a 

 scale modified to form a cornea. The structure of the epiphysis 

 is interesting, being unlike that met with before. In the 

 specimen examined, though the external indication was present, 

 the parietal foramen was seen, when sections through the head 



