64 



FREDERICK TILNEY AND LUTHER F. WARREN 



The cells constituting this solid organ arrange themselves 

 more or less in alveolar or aciniform cell groups and the whole 

 body ultimately becomes attached to the roof -plate by means of 

 a thin stalk or peduncle. No evidence of an anterior evagina- 

 tion representing the parapineal element has been observed nor 

 is there any evidence to show that any effort toward the devel- 

 opment of the parietal eye in Ophidia, Chelonia, or Crocodilia 



Fig. 30 The epiphyseal complex in an older Tropidonotus embryo, according 

 to Leydig, 1897. 



P/., Paraphysis; Ds., dorsal sac; Ch., commissura habemilaris; Ep., proximal 

 portion of pineal gland. 



is present. In fact, in the latter forms, namely, Crocodilia, the 

 entire epiphyseal complex is said to be wanting and no evidence 

 of its development occurs at any time during ontogenesis (figs. 

 31 and 32). 



One of the authors, studying the development of the epiphysis 

 in turtles, reconstructed the forebrain of Thalassochelys caretia 

 in several stages. The conditions in the 30 mm. embryo are 

 shown in figure 33. Here the pineal region consists of a well- 



