BULLFROG AS TYPICAL VERTEBRATE ANIMAL 91 



chiasma is the infundibulum, and somewhat behind this is the vitu 

 itary body, or hypophysis. The pitiiitaiy is of dual origin, developing 

 m part from the diencephalon and in part from the roof of the mouth 

 cavity. The midbrain contains two large rounded optic lobes The 

 ventral part of the brain below these lobes is the crura cerebri. 



Olfactory tract 

 Olfactory lobe 



Cerebrum 



Optic neh-ve 

 Pineal body 



^ -Diencephalon 



Trlqem'inus^ 



Tacial 



Auditory 



Thoracic 

 enlargement 



'Spinal cord 



Lumbar 



^nlanjement 



n/umterminafe, 



Optic lobe 



Cerebellum 



Medulla oblongata 



^^ ventricle 



J?/O55opbaryngea/ 



Vaqus nerve 



J^ Spinal nerve 



2.^ spinal nerve 



Brachial 

 plexus 



3^ spinal nerve 



.+ - spinal nerve 



XalcamoQs body 

 6p\na\ nerve 



Spinal nerve 



~ Spinal nerve 



.^^^ spinal nerve 



3^ spinal nerve 



JOtb spinal nerve 



Sciatic plexus 



Sciatic nerve 



Fig. 30. — Dorsal view of nervous system of a frog. 



The hmdbrain consists of the cerebellum and the medulla oblon- 

 gata. The cerebellum in the frog is almost rudimentary and consists 

 of a transverse fold of tissue immediately posterior to the optic lobes. 

 The cerebellum is in close connection with the large triangular 



