BRAIN 



207 



r.o 



FIG. 155. BRAIN OF MYXINE. (After G. Retzius.) A, dorsal; B, ventral; 

 C, lateral view. The olfactory organ and its cartilaginous skeleton (r.o) is 

 left in situ. 



a, eye ; y.h, ganglion habenulse ; HH, cerebellum; //, vestigial optic nerve; 

 MH, mid-brain ; NH. medulla oblongata ; pi, infundibular process ; r, 

 spinal cord ; rb, olfactory lobe ; s, spinal nerves (dorsal roots and ganglia) ; 

 P, 2 , 3 , trigeminal; VH, teleiicephalon ; VII, facial; VIII, auditory; X, 

 vagus ; A' 1 , sensory branch of vagus or dorsal branch of a spino-occipital 

 nerve. 



