LENSE OF THE PARIETAL EYE. 



145 



FIG. 103. Cross- sections of the procephalic lobes of an embryo scorpion. E, Posterior part of stomodaeal region, 

 showing the third cephalic neuromere, en 3 , the lateral eye ganglion, l.e.g., and the corresponding invagination, and 

 the posterior margin or the palial fold; E f , same stage farther forward, showing the stomodaeal ganglion and its 

 commissure, the second cerebral neuromere, the parietal eye ganglion and its corresponding infolding, iv 2 . Com- 

 pare Fig. 15, B. F and F' are corresponding sections in an older stage, Fig. 16, A, showing the crowding of the 

 lateral eye ganglion over the cerebral neuromeres and the appearance of the parietal eye, p.a.e, t on the inner 

 limb of the palial fold. Camera outlines. 



FIG. 104. Selected sections from a continuous series through the procephalic lobes of an embryo scorpion, in stag 



G (Fig. 1 6, B). Camera outlines. 

 IO 



