158 



COMPARATIVE ANATOMY 



covered by a thickened and vascular portion of the pia mater or 



choroid jplcxus. 



iin ME 



Z.E Gp 



I JE 



U L.ol. 



iSv Eyp 



Fig. 129. — Bkain op Laeval Lampkev. (A, from above ; B, from below ; 

 C, from the side.) 



VH {Bafi.G), cerebral Kemispheres, between which, in A, the median portion of the 

 prosencephalon is seen, with the membranous roof removed ; L.ol, olfactory 

 lobe ; ZH, thalamencephalon ; O.p, pineal body ; Hyp, hypophysis ; Sv, 

 saocus vascnlosus ; MH, mid-brain ; HH, cerebellum ; NH, medulla oblon- 

 gata ; Med, spinal cord ; I-X, crariial nerves ; XH, fitst spinal nerve (hypo- 

 glossal). 



The braiii of Myxine shows nmny special peculiarities: its 

 subdivisions are broader and more closely approximated than in 



