14 
Northcutt 
survive 24 , 48, and 72 hours postoperatively, 
after which time they were perfused with 
AFA (90 cc of 80% ethanol, 5 cc of formalin, 
and 5 cc of glacial acetic acid). The brains 
were removed from the skulls and stored in 
AFA for 1 week prior to dehydration and 
embedding in paraffin. The brains were cut 
in the transverse plane at 15 /a and de- 
fatted. Kodak NTB3 nuclear track emulsion 
was diluted 1 :1 with distilled water at 40° C, 
and the slides were dipped into the emulsion 
and dried for approximately 1 hour. The sec- 
tions were exposed for 20 days and developed 
in Kodak Dektol and stained with cresyl 
violet. 
RESULTS AND DISCUSSION: 
TELENCEPHALON 
This brain division in all reptiles consists 
of paired cerebral hemispheres and a tel- 
encephalon medium, that portion of the 
telencephalon that does not evaginate. The 
olfactory bulbs, which are secondary evagi- 
nations from the cerebral hemispheres, form 
the rostral pole of the telencephalon ( Fig. 1 ) . 
In lizards, these bulbs may be attached to the 
cerebral hemispheres by very long slender 
peduncles, or they may attach directly to the 
hemispheres. Both conditions can occur 
within closely related genera and, thus, are 
unreliable taxonomic characters. 
The cerebral hemispheres are divided into 
a roof (pallium) and a floor (subpallium). 
The pallium can be subdivided into three 
longitudinal cellular cortices : a medial cortex, 
a dorsal cortex, and a lateral cortex; and a 
large ridge of cells protruding into the lateral 
ventricle and termed the dorsal ventricular 
ridge (Figs. 1-3). 
The subpallium is divided into a medial 
zone, including septal nuclei ; a ventral zone, 
including nucleus accumbens and olfactory 
tubercle; and a lateral zone, including the 
striatum and amygdaloid nuclei. Rostrally 
the striatum can be divided into a pars 
dorsalis and a pars ventralis. The pars 
dorsalis of the striatum can be traced to the 
level of the lamina terminalis where it is 
Figure 1. Exploded view of the brain of a teiid, 
Tupinambis, illustrating the relative position of 
major neural centers described in this work. 
c, cerebellum; cd, dorsal cortex; cl, lateral cortex; 
cm, medial cortex; dvr, dorsal ventricular ridge; 
m, medulla; ns, nucleus sphericus; ob, olfactory 
bulb; on, optic nerve; rot, nucleus rotundus; s, 
septum, st, striatum; to, optic tectum. (Figure 
from Northcutt and Senn, in preparation.) 
replaced by part of the amygdaloid complex. 
The pars ventralis of the striatum continues 
more caudally and merges with the fibers of 
the lateral forebrain bundle where its con- 
tinuation is termed the nucleus entopeduncu- 
laris. 
The caudal lateral telencephalic wall is 
formed by a number of nuclei whose embry- 
ology is unclear. These consist of a nucleus 
sphericus, nucleus ventromedialis, and pars 
posterior of the dorsal ventricular ridge. All 
of these nuclei have been considered homo- 
logous to the amygdaloid nuclei of mammals, 
though there is no experimental evidence to 
support this speculation. 
At present two very different theories 
exist regarding the origin and topographical 
relationships of the amygdaloid nuclei in 
vertebrates. Herrick (1948) argued that the 
amygdala of the tiger salamander was the 
caudal continuation of the corpus striatum 
and thus of basal (subpallial) origin. In 
