ELASMOBRANCH BRAIN ORGANIZATION 



129 



on 





'-* >-*--?-~ •-*-'» 



1 mm 



6 5 



1 mm 



Figure 4 Transverse sections through (A) rostral and (B) caudal thalamic levels of 

 Mustelus canis. cp, central pretectal nucleus; cz, central pretectal zone; dt, dorsal thal- 

 amus; fb, forebrain bundles; h, habenular nuclei; he, habenular commissure; it, intertectal 

 commissure; oc, optic chiasm; on, optic nerve; ot, optic tectum; pz, periventricular tectal 

 zone; sp, superficial pretectal nucleus; sz, superficial tectal zone; vt, ventral thalamus; 

 1-6, tectal layers of Gerlach. 



