MORPHOLOGY OF THE FOREBRAIN 443 



Kupffer) is included between the ventral angle of the hemisphere 

 and the fissura limitans hippocampi. It is bounded rostrad by 

 the olfactory bulb and caudad by the lamina terminalis. Within 

 this part there is a highly differentiated cellular mass, the corpus 

 precommissurale or nucleus medialis septi, which extends back- 

 ward dorsally into the lamina terminalis and both below and above 

 the interventricular foramen. These cells form the "bed" of 

 the anterior and dorsal (or anterior pallial) commissures. The 

 portion of the nucleus medianus septi which extends caudad 

 above the foramen is very much enlarged in some species of frogs. 

 It is well named by Kappers ('08) the pars fimbrialis septi, for 

 its cells are in intimate relation with the fimbria fibers passing 

 between the dorso-median and dorso-lateral parts and the ventro- 

 median part which form one component of the complex termed 

 tractus olfactorius septi. 



B. Haller ('08, p. 373) designates this nucleus "Ammonskern" 

 and considers it a part of the "Ammonswulst" or primordial 

 hippocampus. He cites Edinger as teaching that the Ammons- 

 kern alone is the precursor of the hippocampus, but in the last 

 edition of Edinger's Vorlesungen the pars dorso-medialis is desig- 

 nated cortex ('08, p. 306, fig. 276). The ventro-median part 

 receives fibers from the olfactory bulb in front and is broadly 

 connected with the hypothalamus through the median forebrain 

 bundle, both by ascending and by descending tracts which par- 

 tially decussate in the anterior commissure. It also has broad 

 fibrous connections with the other parts of the hemisphere. 



The pars ventro-lateralis is included between the ventral angle 

 of the hemisphere and the fissura endorhinalis (sulcus limitans 

 lateralis, Gaupp). It is bounded rostrad by the olfactory bulb ; 

 the caudal boundary is fixed dorsally by the so-called corpus 

 striatum laterally of the lamina terminalis, while ventrally it 

 passes over without interruption into the prominentia fascicularis 

 (Gaupp) of the thalamus, which is a part of my pars ventralis 

 thalami. In front it receives fibers from the olfactory bulb which 

 for the most part come from the bulbulus accessorius and join 

 to form a compact fascicle of unmedullated fibers which passes 

 backward close to the ventricle and immediately ventral to the 



