418 J. B. JOHNSTON 
core-nucleus. It extends through nearly the whole length of the 
ridge as a large, somewhat quadrilateral area bounded laterally 
by the pyriform lobe and centrally by the cell clusters of the 
ventricular layer Dorsally it is separated from the thickened 
border of the general pallium by a cell-free zone of fibers and 
ventrally it is bounded by the chief fiber mass in the center of 
the ridge. Toward the rostral end of the ridge this body of cells 
becomes separated into two masses in the transverse section, 
owing to the general pallium and lentiform nucleus pressing into 
it from above and below respectively (fig. 22). Caudally this 
mass of cells becomes less distinct and merges with the super- 
ficial cells of the general cortex as noted at first. Throughout 
the greater part of its length this core-nucleus is penetrated by 
numerous fibers which pass up from the internal capsule to the 
thickened lateral border of the general pallium. Although only 
a few such fibers are seen in Weigert sections, a great number 
of non-medullated fibers take this course and they are very 
conspicuous in Cajal preparations. 
Comparison of the turtle brain with that of some lower mam- 
mals leads to the suggestion that the dorsal ventricular ridge is 
the homologue of one of the cell masses which constitute the 
amygdaloid complex in mammals. This is entirely independent of 
the homology of the ‘epistriatum’ with the amygdaloid body sug- 
gested by Kappers and others. This ventricular ridge is a wholly 
different structure from the ‘epistriatum’ of Kappers. This 
matter will be discussed in a later paper dealing with the amyg- 
daloid complex in the opossum and some mammals. To follow 
the comparison here would lead beyond the limits of this paper. 
The amygdaloid complex in the turtle includes the following 
structures: the nucleus of the lateral olfactory tract, the tail of 
the caudate nucleus, the medial large-celled nucleus and prob- 
ably the dorsal ventricular ridge. The amygdaloid eminence 
in the temporal pole is encroached upon by both the hippo- 
campus and the general pallium. The amygdaloid complex 
has related to it the lateral olfactory tract, a bundle of the medial 
olfactory tract, the bundle of the diagonal band, the stria medul- 
