THE FOREBRAIN OF THE ALLIGATOR 347 
tex and the cortex-like superficial layer of the tuberculum ol- 
factorium. Close to its anterior end the cells of the upper or 
more dorsal portion of the nucleus group themselves more close- 
ly together and a clearly defined nucleus is formed which is ven- 
tral to the dorsal-lateral area and lateral to the ventro-lateral 
large celled area. At first this upper portion of the nucleus of 
the lateral olfactory tract remains distinct from the surrounding 
cell masses of the hemisphere wall; but as it is followed caudad 
it gradually comes into close relation with the cell mass of the 
dorso-lateral area and finally merges with it with no sharp de- 
limiting line between the two, a greater and greater number of 
large cells appearing among the small cells in that region until 
apparently the mass has become a part of the dorso-lateral area. 
The ventral portion of the nucleus, at the anterior end of the 
brain, consists of diffuse clusters of cells lying in close relation 
with the pyriform lobe, the cortex of the tuberculum olfactorium, 
and, farther caudad, the nucleus of the diagonal band of Broca. 
At approximately the level of the fusion of the anterior dorsal 
portion of the nucleus of the lateral olfactory tract with the 
dorso-lateral area, the ventral portion of the former nucleus 
broadens out and extends to the posterior end of the hemisphere, 
occupying first a ventro-lateral and then a ventral position. 
A part (probably the more ventral portion) of the anterior 
dorsal portion of this nucleus of the lateral olfactory tract, as it 
has been described for the alligator, is quite probably compar- 
able with the small celled, ventral part of the pyriform lobe 
observed by Johnston (715) in the turtle. In describing this small 
celled part Johnston says that in the rostral part of the brain of 
Cistudo carolina it may be sharply distinguished from the large- 
celled portion both by the difference in cell character between 
the two regions and by the more ventral position of the small 
celled portion, which extends below the sulcus endorhinalis and 
expands behind the posterior part of the striatal area into 
the nucleus of the lateral olfactory tract. In the alligator the 
continuance of the pyriform lobe cortex (Johnston’s large celled 
medial portion) farther ventralward, has pushed this small celled 
portion inward and crowded it somewhat dorsalward so that 
