42 
Northcutt 
7 
Fi^re 15. Photomicrograph of a transverse section through the optic tectum of the green 
iguana, Iguana igvMna. Bodian preparation from a middorsal position at a rostrocau a 
level similar to tectal level D in figure 1. P, periventricular zone; C, central zone; b, super- 
ficial zone. Numbers to right of figure identify individual laminae after the nomenclature 
of P. Ramon (1896) and Senn (1968). Bar scale represents 100 fi. Note reduced cellular 
laminae in periventricular zone, migrated neurons in upper half of central zone and thic - 
ened zone 14. These tectal features characterize the Iguania as well as teiids and varamds. 
