176 Journal of Comparative Neurology. 



Fig. J. Drawing of a part of the cerebral wall from an embry dog. 

 The portion selected is from the frontal region and illustrates a similar 

 process in a later stage. 



F/gs. I and j. [204-7, 8.] Nearly perpendicular longitudinal sections 

 through the head of embryonic black-snake (Plate XVI, Figs. 6, 7.) 

 Both sections are hear the lateral surface, Fig. 5 being the deeper. The 

 neuromerism of the medulla is well shown. 



Figs. 6 and 7. [202-7.] These figures are from the four or five day 

 chick embryo for comparison with those of Plate XVII. Tne chick is 

 obviously in a somewhat later stage. The flexures are apparently less, but 

 this is due to a backward revolution of the cerebral end. 



F/'gs. S. [205-3.] Horizontal section of the fore-head of a black- 

 snake embryo (Figs, 6, 7, Plaie X\'I.) The formation of the lateral ves- 

 icles and the distinctly double character of the diencephalon are note- 

 w^orthy. 



Fig. g. [208-9.] Section similar to Fig. i, from oldest Futi\;nia 

 embryo. The section is immediately in front of the hypophysis and 

 shows the upper jaw rudiments. 



Fig. 10. Section through the auditory capsules of the Eutienia em- 

 bryo figured Plate XJ'I, Fig. 3. The hyoid centrum is forming at H. 

 Au. auditory vesicle. 



