A CASE OF CYCLOPIA 



213 



The relation of this roof to the thalamic mass as subsequently 

 determined may be seen by comparing a sagittal section (fig. 11) 

 with a surface view from above and in front (fig. 14). 



It will be seen that there is a discontinuity of the ventricular 

 system in this region so that the large cavity of the primary fore 

 brain vesicle is not in connection with the iter. The line of 

 attachment of the thin roof to the surface of the thalamic mass 



Cor.cer. 



Fig. 14 Diagram of posterior portion of forebrain seen from above and in 

 front. The thin roof has been removed and the point of its attachment to the 

 cerebrum and thalamic mass is indicated in dotted lines. Cor.cer., cortex cere- 

 bri; Cor. pin., pineal body; T.c, taenia cerebri; Th.ex., extraventricular portion 

 of the thalamus; Th.in., intraventricular portion of the thalamus; Vent. I., cav- 

 ity of cerebral vesicle. 



corresponds to the taenia thalami. The taeniae become contin- 

 uous with one another some distance in front of the pineal body. 

 At the point of junction between the thalamic mass and the 

 cerebrum, the roof is attached to the margin of the latter struc- 

 ture and the taenia thalami becomes continuous with the fimbria. 

 In the diagrams (figs. 11, 12 and 13), the basal plate of the 

 cerebrum is represented as split into two laminae. This split- 

 ting apparently occurred during fixation and the line of cleavage 

 passes in most cases through the portion repesenting the medul- 

 lary center. 



THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 23, NO. 3 



