VoiA^MF, XII 1902. Number i 



THE 



Journal of Comparative Neurology. 



THE BRAIN 0¥ PETROMYZON. 

 By J. B. Johnston, 



Professor of Biology, PVest Virginia University. 

 With Phites 1— Vlll. 



Table of Contents. 



PA UK 

 I. iNTRfinUCTIOX . . . . . .2 



II. Gknkkal Description . . . . . .4 



III. Minute Anatomy ...... 9 



A. Hind Brain ....... 9 



a. Motor nuclei and motor nerve roots . . 9 



b. The Miillerian fibers . . . . .12 



c. ( General and special cutaneous centers (somatic), 



Topography .... 14 



1. Nucleus funiculi . . . . .16 



2. Nucleus trigemini spinalis ... 16 



3. Tuberculum acusticum, sensory endings in . 17 



4. Cerebellum ..... 20 



d. Internal arcuate libers . . . . .23 



e. Fasciculus communis (visceral and end-bud) center 23 



f. Lower olive . - . • . • -5 



B. Mid Brain . . . . . .26 



a. Tectum opticum, fiber tracts of . . .26 



b. Central grey and comnnssura posterior . . 29 



c. Commissura ansulata . . . . -3° 



C. ' T-iveen Brain ...... 3° 



a. Ganglia habenulae and the bundles of Meynert, Epiphysis 30 



b. Thalamus ...... 3" 



c. Hypothalamus . . . . . .3" 



Lobi inferiores ..... 3^ 



Corpus manimillare . . . . -37 



Fore brain tracts ..... 37 



Saccus . . . . . . -3° 



Postoptic decussations .... 39 



y). Fore Brain . . . . • ■ -39 



a. Corpus striatum . . . . • 39 



