356 ELIZABETH CAROLINE CROSBY 
the dorso-medial cortical area extends forward into the region 
just posterior to the olfactory crus and the primordium hippo- 
eampi, though quite plainly present, is relatively smaller than 
in the turtle. This means that in the alligator the hippocampus 
in this region is more highly specialized than in the turtle. The 
cells making up the primordium hippocampi are small and are 
arranged in a diffuse mass. They are not impregnated in the 
Golgi preparations which were studied. 
Pyriform lobe (figs. 3 to 10, 12, 14 to 19). The pyriform obe 
has important functions both as a secondary olfactory center 
and as a correlation mechanism of high order. By means of 
connections with the olfactory bulb and the basal and cortical 
centers of the hemisphere it receives both correlated and uncor- 
related olfactory material. By means of its connection with the 
tuberculum olfactorium and, also, through short correlation fibers 
from the somatic centers of the hemisphere, t receives corre- 
lated somatic material. It receives impulses from the other 
cortical centers by way of the alveus. Consequently it serves, 
in part at least, as an olfacto-somatic correlation center of high 
order. 
In the anterior end of the hemisphere, in the region of the ol- 
factory lobe, the pyriform lobe cortex and the hippocampal cor- 
tex lie in close relation with each other dorsally. They are soon 
separated, however, by the general pallium which intervenes 
between them throughout the remaining extent of the hemis- 
phere. Ventrally the pyriform lobe les in close relation with 
the tuberculum olfactorium, separated from it only by some 
scattered cells of the anterior division of the nucleus of the lateral 
olfactory tract. Behind the tuberculum olfactorium, the cortex 
of the pyriform lobe is bounded ventrally by the nucleus of the 
diagonal band of Broca and by the nucleus of the lateral olfac- 
tory tract. Near the posterior end of the hemisphere, this latter 
nucleus, which there occupies all the ventral surface excepting 
the portion occupied by the ventro-medial nucleus, acquires 
a cortex-like arrangement of its superficial cells (fig. 12) which 
layer is continuous with the cortex of the pyriform lobe and to 
all intents and purposes is a part of that area since the pyriform 
