The Nervous System of Amblystoma. 



469 



Fig. 11. A is a section through the eyes and optic lobes, B is a portion of the 

 inner wall of the eye shown in A greatly enlarged to give the cell structure, C 

 is a portion of the open neural plate seen in cross section showing the structure 

 of the neural crest and peripheral groove, e, eye; nc, neural crest; ol, optic lobe; 

 pg, peripheral groove. 



on the surface of the neural plate. An examination of the sur- 

 face views of the stage in which the primary brain vesicles are 

 beginning to appear shows this groove lying just behind the 

 cerebellar swelling of the neural crest (fig. 8). An embryo that 

 has been split in halves shows this relation to better effect (fig. 

 9, C). Behind the fourth neuromere is the transverse cephalic 

 groove (teg). Directly above the fourth neuromere is the cere- 

 bellar crest (c.) A careful examination of Plate 1, fig. 15, shows 

 the cerebellar crest and its relation to the posterior boundary of 

 the procephalic lobes exactly as in the figures just described. The 



