Fig 1 Reconstruction of the middle plane of the brain, Jogether ^^ 

 cho-d and hypophysis in Squalus acanthias embryo, 40 mm. total lengt 



Fig. 2 Medial plane reconstruction of the brain, notochord, and hy 

 in a chick of seven and one-half days' incubation. X 10. 



Fig 3 J^Iedial plane reconstruction of the brain, hypophysis, notoc 

 basilar plate in a calf embryo of 23 mm. length. (Series C.25, Cornell V 



Collection.) XlO. „ , i . 



In these figures the floor-plate is indicated by the parallel, somewhat 

 lines representing the fibers of the floor-plate. 



118 



ith noto- 

 h. XlO. 

 pophysis 



hord and 

 niversity 



irregular 



