THE FOREBRAIN OF THE ALLIGATOR 369 
are on the superficial or pial side of the layer of cortical cells. 
Near the anterior end of the hemisphere short association fibers 
pass between the dorso-medial portion of the hippocampus and 
the general cortex. 
These short superficial association fibers convey the nervous 
impulses which probably have operated in the course of the 
phylogeny to draw the cells of the primordial neopallium from 
the ventricular to the superficial position (neurobiotaxis; cf. the 
preceding discussion of the general cortex). 
Fornix 
In the fornix system of the alligator three parts have been dis- 
tinguished. The first of these is the commissura hippocampi 
(commissura fornicis), which has already been described. The 
other parts are the columna fornicis and the fornix longus. 
Columna fornicis (figs. 18 to 21, F). The fibers making up 
this division of the fornix are mainly axones of the double pyra- 
mid cells and small projection cells of the hippocampus. As 
has been said before, the fornix fibers join the hippocampal com- 
missure and the tractus cortico-habenularis medialis. They 
swing first slightly lateralward and then medio-ventralward. 
Below the foramen of Monro the columna fornicis fibers sepa- 
rate trom those of the hippocampal commissure and, running 
caudad, enter the hypothalamus. They are accompanied by 
the fibers of the olfactory projection tract of Cajal (figs. 19 to 
2 
The description here given agrees with the relations brought 
out by C. J. Herrick (10). The myelinated fibers of the fornix 
have been described again and again by workers on the reptil- 
ian brain, among the number being Rabl-Riickhard (’81), Edin- 
ger (88 and ’96), C. L. Herrick (’93), Adolf Meyer (’92), Unger 
(06), and DeLange (11). 
Fornix longus (figs. 16, 17, F.L.). This term is applied in 
mammals to a diffuse collection of fibers of mixed character pass- 
ing in the medial wall of the hemisphere between the precom- 
missural hippocampus (and adjacent parts of the cortex) and 
