PAEAPHYSIS AND PINEAL REGION IN REPTILIA 361 



Kupffer (57) states that it enters a swelling in the median wall 

 of the hemisphere which represents the embryonic hippocampus 

 of mammals. Kupffer (57) shows it in figs. 248 and 265, sagittal 

 sections of Anguis, and in 259, a transverse section of Anguis. 

 The latter figure illustrates its course clearly and as it crosses 

 the median line it is bounded cephalad by the wall of the paraphy- 

 sis and caudad by the single layer of cells forming the caudal wall 

 of the velum. Kupffer states that laterally a part of the fibers 

 enters the ''Eminentia medialis" in the medial wall of the hemi- 

 sphere, while another part probably enters the stria medullaris, 

 but owing to the presence of other fiber tracts he thinks the exact 

 composition of the commissure is not clear. I have seen a sim- 

 ilar section to fig. 259 in H. E. C, no. 1604, Lacerta muralis. 

 G. Elliot Smith (88) described very thoroughly this commissure 

 in Sphenodon and called it an aberrant commissure, ' Commissura 

 aberrans.' Dendy (18) mentioned this commissure also in 

 Sphenodon and called it Commissura fornicis. Elliot Smith's 

 figs. 1 and 2 give a good view in the sagittal plane and show how 

 the commissure makes a striking rounded swelling in the velum, 

 which forms a marked projection between the opening of the para- 

 physis and the post velar arch. He describes two masses of 

 gray matter in the mesial wall of the hemisphere as the parater- 

 minal bodies which are connected by the lamina terminalis (88), 

 figs. 4, 5 and 6. Above these structures in the mesial wall of the 

 hemisphere is the region of the hippocampus, below them the 

 corpus striatum. The figures show the relations of the commis- 

 sura dorsalis and ventralis to these structures and to the ven- 

 tricles In fig. 10 the aberrant commissure appears at a later 

 stage and the writer states that it crosses over the ventricle in 

 the bridge of gray matter formed by the fusion of the caudal 

 extremities of the paraterminal bodies. After passing through 

 the paraterminal body the fibers end in the hippocampus in a 

 manner exactly analogous to that which characterizes the com- 

 missura dorsalis in the most cephalic region of the hippocampus. 

 He concludes that the commissure is derived from the caudal 

 end of the hippocampus and crosses by the more direct route via 

 the velum rather than by the longer one via the lamina terminalis 



THE AMERICAN JOUKNAl. OF ANATOMY, VOL. 11, NO. 4 



