466 



Leland Griggs. 



10 



Fig. 9. Later stages in the closing of the neural canal and the development 

 of the cerebral vesicles. C is a view of the inside of a halved neural tube, and 

 D is a view from the side of an entire embryo, anp, anterior neuropore; c, cere- 

 bellar crest; e, eye; fb, fore-brain; nl, n2, n3, n4, neuromeres of the procephalie 

 lobes; ol, optic lobe; rs, retinal spot; teg, transverse cephalic groove. 



Fig. 10. Sections to show the structure of the walls of the neural canal. The 

 diagram A shows the location of sections B and C. C is an older embryo than B. 

 The diagram D shows the location of sections E, F and G. F is an older embryo 

 than E, and G is older than F. e, eye; c, cerebellar crest; mbl, mb2, divisions 

 in the optic lobes or mid-brain; ol, optic lobes. 



