30 
Northcutt 
The dorsal striatal component primarily 
consists of medium-sized cells with little or 
no AChE activity. The neuropil surround- 
ing these neurons is characterized by mod- 
erate AChE activity. A specialized neural 
lamina or crescent is particularly obvious in 
the dorsal striatal component of Iguana. At 
mid-telencephalic levels, a particularly con- 
spicuous clustering of cells occurs within the 
medial half of the dorsal component charac- 
terized by high AChE activity. This high 
density crescent is thus sandwiched between 
dorsal and ventral moderate AChE zones. A 
similar, but more diffuse, crescent was iden- 
tified in Gekko. 
The ventral striatal component is charac- 
terized by high AChE concentrations and 
can be divided into dorsomedial small-celled 
and ventrolateral large-celled zones. The 
large-celled zone has been recognized by most 
workers (Crosby, 1917; Northcutt, 1967; 
Hoogland, 1975). The cells possess high con- 
centrations of AChE and are particularly 
obvious as they are scattered among the 
fibers of the lateral forebrain bundle which 
demonstrates little or no AChE activity. 
At present, little is known regarding the 
afferent and efferent connections of the 
striatum. Hoogland (1975) has reported ex- 
tensive dorsal ventricular ridge projections 
to the striatum of Tupinambis. Distel and 
Ebbesson (1975, personal communication) 
have reported visual and auditory projec- 
tions via nucleus rotundus and nucleus re- 
uniens to the striatum of Varanus. 
The only detailed study of the striatal ef- 
ferents in a lizard is that of Hoogland 
(1975). He reports striatal projections to 
nucleus rotundus, habenula, nucleus ventro- 
medialis, nucleus entopeduncularis, substan- 
tia nigra, mesencephalic gray, and lateral 
cerebellar nucleus. For the most part, these 
projections closely match the projections of 
the striatum in mammals and suggest that a 
fully developed ansa lenticularis is present 
in lizards. 
The striatum of Iguana is better differen- 
tiated than that of Gekko. However, since 
recognition of cytological divisions of the 
striatum is heavily dependent on histochem- 
ical analysis, it is presently impossible to 
determine the range of variation among liz- 
ards. Since the dorsal ventricular ridge pro- 
jects to the striatum, it is likely that hyper- 
trophy of the ridge leads to hypertrophy of 
the striatum as well. In birds, the ridge pro- 
jects only to the dorsal division of the stria- 
tum, which, in turn, projects to the ventral 
division of the striatum, which gives rise to 
the ansa lenticularis complex (Karten and 
Dubbeldam, 1973). More detailed analysis of 
telencephalic efferents are needed in lizards 
to decide if a similar pattern exists. If a simi- 
lar pattern of connections does exist in liz- 
ards, it would provide strong evidence that 
the dorsal striatal component is homologous 
to the caudate and putamen nuclei of mam- 
mals, and that the ventral striatal component 
is homologous to part of the globus pallidus 
of mammals. 
The septal nuclei. Most studies have recog- 
nized at least two divisions of the septum, 
lateral and medial septal nuclei. However, 
even a cursory examination of the septal 
complex in reptiles suggests that this region 
contains more than two recognizable divi- 
sions. The septal complex is particularly dif- 
ficult to subdivide due to the number of fiber 
systems either terminating within this com- 
plex or passing through it. Reasonable sub- 
division will be possible only as experimental 
analysis reveals major terminal sites of in- 
coming fibers and septal zones that give rise 
to major efferent projections. 
Recently Ulinski (1975) reported on the 
corticoseptal projections in Matrix and 
Thamnophis. Medial cortex projects bilater- 
ally to a dorsal portion of the precommis- 
sural septum with the ipsilateral projection 
being the more massive. A division of dorsal 
cortex also projects ipsilaterally to a dorsal 
portion of the septum caudal to the level of 
the anterior commissure. This terminal site 
shifts ventrally in the septum as it is followed 
rostrally. Ulinski also reported on a possible 
sparse projection to the ipsilateral ventral 
septum from the lateral cortex. Lohman and 
Mentink (1972) and Lohman and Van 
Woerden-Verkley (1976) have reported 
