134 MARION HINES 
ment of the lateral plexus as the hemispheres come more and more to 
dominate the development of the telencephalon (pp. 526 and 527). 
However, it dominates only because of the progressively in- 
creasing importance of the portion of the hippocampus which is 
developing in the ventro-caudal direction concomitant with the 
growth of the hemisphere in that same direction to form the 
Fig. 19 Median sagittal view of a model made from the brain of a 43-mm. 
human embryo belonging to the Mall collection, no. 886. X 62. 
temporal lobe. It seems more reasonable, therefore, to place 
the anlage of the telencephalic lateral plexuses, even in man, 
in the epithelial tissue which lies between the taenia fornicis or 
the sulcus limitans hippocampi and the paraphyseal arch and 
velum transversum and limited rostro-caudally by the anterior 
limb of the paraphyseal arch and the velum transversum. From 
this dorsally placed anlage it grows ventro-caudally. If this be 
true, the primordium of both divisions of the two lateral choroid 
plexuses lies immediately contiguous to the roof plate of the early 
unevaginated telencephalon. 
