ANATOMY OF A CYCLOSTOME BRAIN 



671 



uiiclcrlying deep structures are indicated by rows of crosses. Similarly, the ven- 

 tral boundary of that portion of the cell plate constituting the primordial corpus 

 striatum {c.s.) which lies contiguous to the ependymal surface is indicated by 

 a row of crosses. This cell plate extends farther ventrally and posteriorly than 

 here indicated, but separated from the surface by other structures. The position 

 of the fasciculus retroflexus of Meynert (/. retrof.), or tractus habenulopeduncu- 

 laris, is also shown as projected upon the ventricular surface. The five giant 

 cells of Miiller which lie within the limits of the model are indicated by double 

 cross-hatched areas (1 to 5). The epiphyseal stalk (ep.s.) is drawn somewhat ex- 

 aggerated in size and farther removed from the membranous wall of the dorsal 

 sac than is natural. On the scales at the top and bottom of the figure are indi- 

 cated the levels at which figures 5 to 12 were taken. 



Fig. 4 View of the medial surface of the right half of the model after flivision 

 in the sagittal plane. X 50. 



