AMPHIBIA. 65 



1. Anterior lobes of the brain from which the olfactory nerves proceed. 



2. Thalami of the optic nerves. 



3. Optic lobes. 



4. A narrow transverse band, which is the cerebellum, and behind this the 



ventricle at the calamus scriptorius. 



5. A large nerve, instead of the axillary plexus: it is formed of an anterior and 



posterior bundle, the posterior having a ganglion attached to it. The cauda 

 equina is seen forming the nerves of the lower extremities. 



6. Anterior crural nerve. 



7. Sciatic nerve: some of the white vesicles are seen, which are supposed to 



contain cretaceous matter. 



FIG. VII. 



THE BEAIN OF THE SNAKE. 



(BOA CONSTRICTOR.) 



1. STRIATED body and oblong eminence near the middle line, seen as in the turtle, 



on opening the lateral ventricle. 



2. Optic lobe opened. 



3. Cerebellum extending over the ventricle at the calamus scriptorius : the sides 



of the ventricle have been rather too much separated. 



