CELL MASSES IN THE FOREBRAIN 395 
The dorsal border of this depression is formed by a low ridge 
which extends rostrally into the lateral wall of the olfactory bulb. 
This ridge is traversed by the lateral olfactory tract and is there- 
fore to be compared with the pyriform lobe of the mammalian 
brain. Near its rostral end it presents an apparent thickening 
which causes a decided elevation of the surface (figs. 5, 26). 
The sulcus which bounds the pyriform lobe dorso-laterally varies 
in depth in different individuals, but is always well marked in 
its rostral portion. It is the fissura rhinalis. 
The insula-like region is clearly seen in the entire brain to be 
trasversed by bundles of medullated fibers (fig. 1). Sections 
show these to be a continuation of the crus cerebri (figs. 32, 49), 
and therefore comparable to the capsula interna. The absence 
of a cortical layer covering the internal capsule shows that this 
does not correspond to the insula. It is the corpus striatum 
which retains a condition analogous to that seen in the fish 
brain and is not yet covered in by pallium. 
Caudal to the striatum there is a well-developed occipito- 
temporal pole whose presence adds to the similitude of the 
turtle’s brain to that of amammal. The pyriform lobe appears 
to blend with the occipital lobe. Along its.lower border is a 
groove which at the rostral end is the sulcus endorhinalis. Be- 
hind the striated area a deep groove continues for some distance 
toward the caudal pole. This groove will be called the fissura 
amygdaloidea. A part of the area appearing below it in lateral 
view is occupied by the amygdaloid complex (fig. 5). The 
reason for calling this the amygdaloid fissure, however, is that 
it represents the line of infolding of an important body which 
becomes in mammals a part of the amygdaloid complex. 
Rostral to the striated area appears the smooth lateral sur- 
face of the tuberculum olfactorium and adjacent olfactory area, 
including the lateral portion of the homologue of the anterior 
perforate space. Between this region and the pyriform lobe 
rostral to the striatum is the sulcus endorhinalis (figs. 19 to 26). 
The vault of the hemisphere is occupied, as we shall see, by 
the general pallium. It is very evident that if the expansion of 
the general pallium were to push the pyriform lobe ventro-later- 
