194 



ZOOLOGY 



membranes have been removed (A), but in the entire organ (B) 

 are roofed over by a conical, tent-like choroid i^lexus (ch. plx. 1). 

 The cavities of the small, spindle-shaped hemispheres (crb. A.) com- 

 municate with the third ventricle by wide foramina of Monro 



Fin. 851.— CaUorhynclius antEircticus. A, dorsal view of brain after removal of the mem- 

 branes ; B, side view with the membranes in place, chlm. cerebellum ; ch. pix. 1, choroid 

 plexus of fore-brain, and ch. 'plx. S, of hind-brain ; cp. rsl-. corpus restiforme ; cp. str. corpus 

 striatum ; crb. h. cerebral hemisphere ; di. coe. diaccele ; di^n. dicncephalon ; for. M. foramen 

 of Monro ; lb. inf. lobus Inferior; med. ohl. medulla oblongata ; mt. coe. metacoslc ; Nv. 2, optic 

 nerve ; Nv. .5, trigeminal ; Nv. 8, auditory ; Nv. 10, vagus ; olf. I. olfactory bulb ; olf. p. 

 olfactory peduncle ; opt. I. optic lobe ; pn. b. pineal body ; pn. .t. pineal stalk ; pty. pituitary 

 body. 



{for.M), partly blocked up by hemispherical corpora striata {cp. str.). 

 Each hemisphere is continued in front into a delicate thin-walled 

 tube, the olfactory pedimclc {olf. pi-), bearing at its extremity a 

 compressed olfactory bulb {olf. I.). 



