SEPTUM, HIPPOCAMPUS, PALLIAL COMMISSURES 377 



the choro'id plexus with the lamina containing the dorsal com- 

 missure. To this recess Burckhardt gave the name recessus 

 neuroporicus and to the ependymal membrane which stretches 

 from this recess to the paraphysis he gave the name lamina 

 supraneuroporica. Burckhardt ('94 c) then compared this epen- 

 dymal lamina supraneuroporica with the tela chorioidea of vari- 

 ous fishes, implying that the neuroporic recess was located at 

 the point of attachment of the tela to the massive roof in front. 

 In all this Burckhardt was in agreement w4th His 1893. In his 

 last work, however, Burckhardt ('07) clearly described the neuro- 

 poric recess in Scymnus and shows that in selachians the lamina 

 supraneuroporica is a true nervous structure. It is in this sense 

 that the term lamina supraneuroporica must be used and not 

 in the sense in which Burckhardt first used it. 



In the meantime Elliot Smith ('96 a, '99) following Burck- 

 hardt, identified the recessus superior of mammalian brains with 

 the angulus terminalis of His and with the recessus neuroporicus. 

 There can be no doubt that the recessus superior is the same 

 as the angulus terminalis (figs. 8, 9, m) and that it corresponds 

 to the recess which Burckhardt called neuroporic recess in rep- 

 tiles. In both classes this recess lies just over the dorsal telen- 

 cephalic commissure and is bounded above by the tela chori- 

 oidea, as clearly figured by Elliot Smith. That it does not 

 correspond to what is known to be the neuroporic recess of 

 selachians is obvious, since in the latter case the neuroporic recess 

 is separated from the tela chorioidea by a thickened lamina con- 

 taining the dorsal commissures. 



The chief contribution by v. Kupffer in this connection was 

 his pointing out the importance of the neuroporic recess as a 

 landmark in forebrain morphology. His in 1892 presented a 

 clear conception of the neural tube as closed rostrally by the 

 lamina terminalis within whose extent the neuropore appeared 

 in some animals. In 1893 he inadvertently abandoned this defi- 

 nition by placing the neuropore at the dorsal border of the 

 lamina terminalis where the latter meets the choroid plexus. 

 Since then some authors have defined the lamina terminalis as 

 the membrane formed by the closing of the neuropore and bounded 



