174 Journal of Comparative Neurology. 



J^'ig. g. Epilhelium over the area from wliicli tlie olfactory pit is to 

 form, in youngest embryos of Eutajnia. [206-4]. 



The space between the epithelium and the cerebrum is occupied by 

 the undifferentiated embryonic material. 



/•y^.f. jo-ii. Portions of the olfactory epithelium in the middle stage 

 of Eutainia showing the origin and migration of the ganglion cells 

 whence the olfactory nerve arises and passes to the tuber. [210-12]. 



PLATE XVE 



This plate illustrates the external ajipearance of the four broods of 

 snake embryos described. 



Fig. I. Entire germinal disc and embryo of the youngest Euta-nia 

 (E. I) moderately enlarged. 



Fig. 2. Head of the same, enlarged. 



Fig. J. Embryo of the same species, two days later. 



Figs 4-j. Embryo of the same species four days later than Eig. 3*. 

 ■ Figs. 6-7. lUack snake embryo taken July 19th. 



PLATE XVIL 



A series of perpendicular longitudinal sections through a Eutamia 

 embryo of the age figured in Plate X\'L Eig. 3. The sections are taken 

 in such a way that, on account of the lateral curvature of the specimens, 

 (compare Eig. 5, Plate XVT) the medulla is obliquely cut. The position 

 of the median line is indicated by a star (*) in the several sections. 

 [209-7, 6, 5]. 



In Eig. I, the eye and ear vesicles are cut. Especial attention is 

 called to the connection of the pituitary and nasal sac via a continuous 

 columnar epithelium. 



Ftg J, especially illustrates the development of the trigeminal sys- 

 tem. 



Figs. 4 and 5 show the neuromeres of the medulla distinctly, — while 

 Fig. 6, which is nearly mcsal in front, has the theoretical axis of the 



*lt should lio added IlKit tlic ynunj,' ;in' not licini until the latter part of .July. 

 July 22, l.S!)2, the young were fairly well developed and liad two rows of dark spots on 

 the dorson and splotche.s on the sides instead of the stripes. The snakes were capable 

 of motion though about one-quarter of the yolk remained. The shell is transparent, 

 not white lilce that of the black snake. It seems legitimate to infer that the progeni- 

 tors of Entienia were spotted like the Tropidoiiotus group. 



