206 



COMPARATIVE ANATOMY 



Oh 



tf 2 & 1 



* 



i^ rprn >* 

 VM I y \ \ r | 

 VHVI M 



tiv U'yp 

 C 



FIG. 154. BRAIN OF LARVAL LAMPREY. A, from above ; B, from below; 

 C, from the side. 



Ghb, ganglion habenulse ; Op, pineal organ ; HH, cerebellum ; Hyp, hypophysis ; 

 L.ol, olfactory lobe ; Afed, spinal cord; MH, mid-brain; NH, medulla 

 oblongata ; S l , S 2 , first and second spinal nerves ; Sv, saccus vasculosus ; 

 VH (Bas.G), cerebral hemispheres between which, in A, the median portion 

 of the telencephalon is seen, with the pallium removed ; ZH, diencephalon ; 

 I-X, cerebral nerves. 



blindly in it .anteriorly. The cerebellum is relatively much larger 

 than in the Lamprey, and projects posteriorly so as to cover the 

 fourth ventricle completely : it resembles that in certain embryonic 



