Susanna Phelps Gage 433 



only through the stalk, the two together forming a lohiile. Even at the 

 point where the eyes approach the skin, they are separated from it by a 

 thin layer of mesoderm (Fig. 16). The lens thickening has only a slight 

 development, showing no tendency to bend towards the eye. Its borders 

 are ill-defined. 



4. Striatal. — A deep fold separates the visual region from the cerebral. 

 On the side of the fold toward the cerebrum is a smaller total fold cross- 

 ing the middle line (Fig. 4). From a careful comparative study this is 

 identified with the fold later bordering the striatum. 



5, 6. Olfactory and Cerebral. — In Figs. 4, 7, are shown the slight total 

 folds, the forerunners of the olfactory and cerebral regions proper. Each 

 pair of folds, begins in a mesal pocket but does not pass far across the 

 brain tube. Mall" considers these among the artificial fissures of the 

 cerebrum but in fact only one of them is cerebral and it represents the 

 whole of that organ. 



Relatively to the dorsimesal line, the three folds included in the 

 cerebral lobule are seen to be caudad of the eye or as expressed by 

 Studnicka,'" they are dorsal. 



While the neural plate is still open it was found both in man and 

 mouse that the region of the cerebrum and also of the diencephal (see 

 above. Cephalic End of Brain Tube) is comprised in a narrow undifl'er- 

 entiated flap beyond the eye and including a portion of the margin. The 

 flap becomes relatively wide before closure and shows some total folds 

 which need more careful identification. 



The olfactory epithelium shown in Fig, 3 has an irregular H-shape 

 with a bar across the meson. This seems to agree with the idea that the 

 olfactory epithelium shifts from the margin to its final, lateral position. 

 Bedford °° has in the pig, found a certain amount of lateral shifting of 

 the olfactory plate, van Wijhe °' found that in shark, both olfactory 

 organs and nerve arise out of the neuropore, thus lending confirmation to 

 the fact shown in this specimen. 



7, 8. Diencephalic. — Are the two folds seen in the roof of the dien- 

 cephal, each meeting its fellow of the opposite side, in the dorsimeson, 

 7, is in the region which ultimately forms the membranous roof and 8, 

 is apparently to form the epiphysial outgrowth from its mesal pocket 

 (cf. Minot"*). 



"Mall, F. P., Amer. Jour. Anat., II, 1903. 



=^« Bedford, E. A., Jour. Comp. Neur. & Psych., XIV, 1904. 



^•■van Wijhe, J. W., Zool. Anz., IX, 1886. 



"'Minot, C. S., Science, N. S., XIV, 1901. 



