THE FOREBRAIN OF THE ALLIGATOR 341 
Nucleus of the diagonal band of Broca (figs. 8, 9, 17). This 
nucleus was first described for reptilian brains by Johnston (’15) 
in the turtle, Cistudo carolina. It is present in the alligator 
in practically the same relations as in the turtle. It appears 
behind the level of the tuberculum olfactorium as a dense col- 
lection of cells arranged in a cortex-like layer in the ventro-me- 
dial angle of the hemisphere. It extends dorsalward along the 
medial surface as a somewhat less dense, cortex-like layer which 
comes into relation with the medial parolfactory area and can- 
not be sharply distinguished dorsalward from the cell mass of 
the primordial hippocampus. It extends from the ventro-me- 
dial region lateralward, as scattered clusters of cells, into rela- 
tionship with the nucleus of the lateral olfactory tract. The 
nucleus of the diagonal band extends posteriorly just outside 
of the medial forebrain bundle into the region of the preoptic 
nucleus. It is accompanied, as in the turtle, by bundles of 
fibers which serve for connecting the lateral and medial olfac- 
tory areas. The writer is particularly indebted to Dr. C. J. 
Herrick for aid in identifying this nucleus in the alligator. 
Basal nuclei of the lateral wall. Students of the reptilian brain - 
have generally recognized two basal centers in the lateral wall 
of the cerebral hemisphere, the corpus striatum and the epi- 
striatum, and some have recognized a third region distinct from 
both of these, comparable with the mammalian nucleus amygda- 
lae. According to these observers, the epistriatum is the more 
dorsal member of the complex and is in continuity with the cor- 
tical lamina. The extent of this continuity varies in different 
reptiles, depending upon the species and the general form relations 
of the hemisphere, particularly upon the ventro-lateral extent 
of the ventricle. In Testudo graeca, DeLange (13a, p. 113, 
fig. 8.) has shown that the epistriatum is continuous with the 
lateral or pyriform lobe cortex throughout its whole extent. 
Kappers and DeLange consider the epistriatum to be striatal 
in origin and to have acquired secondarily a connection with the 
cortical lamina. They consider the epistriatum an olfactory 
nucleus of the second order and the entire epistriatum complex 
the homologue of the mammalian nucleus amygdalae. 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 27, NO. 3 
