248 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



corpus mammillare, infundibulum, lobi inferiores, saccue 

 vasculosus and pituitary body). 



D. Fore -Brain. — This may be considered as including 

 tbe epistriatum, striatum proper and tbe membranous 

 pallium, together with tbe bulbus olfactorius. 



Tbe roots of tbe cranial nerves will be described in 

 tbe section on tbe nerves. 



In a dorsal view of a well-preserved brain we note tbe 

 following characters: — First tbe relatively small size of 

 tbe brain. This is seen also in tbe Cod and in Teleosts 

 generally. Tbe small brain lies in tbe large cerebral 

 cavity, surrounded by a packing of areolar connective 

 tissue loaded with fat, and seems to be very dispropor- 

 tionate to tbe size of the fish. Then the asymmetry of it 

 is at once striking. The spinal cord, on entering the 

 brain case, turns slightly to the left, but opposite the 

 cerebellum it swerves markedly to the right, so that a 

 median line would pass through the left striatum instead 

 of between the two striata. 



In the medulla the great reduction of the terminal 

 bud system that has taken place involves the absence of 

 the lobi vagi. Also the lateral line system is not suffi- 

 ciently robust to have produced that exaggeration of the 

 tuberculum acusticum known as the lobus linear lateralis. 

 Tbe medulla is therefore smooth, and presents no obvious 

 traces of its ganglia. On removing the vascular covering 

 of the fourth ventricle known as the choroid roof, the 

 ventricle itself is seen to be apparently divided into two 

 parts by the partial union over its roof of the medio-lateral 

 portions of the tuberculum acusticum, forming an elliptic- 

 shaped opening behind (calamus scriptorius) and a 

 triangular one in front, with its apex directed backwards. 

 The cerebellum, of which the body only is visible in the 

 undissected brain, is small and globular. This is what 



