104 



coipiis niaiiimillaie, infiuulibuhiiu, l()l)i iuiViIores, saccus 

 vasculosus and pituitary body). 



T>. Fore -Brain.- — -This may bo considered as including 

 the epistriatuni, striatum proper and the membranous 

 pallium, together Avith the bulbus olfactorius. 



The roots of the cranial nerves will be described in 

 the section on the nerves. 



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

 following characters: — First the relatively small size of 

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

 generally. The small brain lies in the large cerebral 

 cavity, surrounded by a packing of areolar connective 

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

 tionate to the 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 sj'stem is not suHi- 

 ciently robust to have produced that exaggeration of the 

 tuberculum acusticum known as the lobus linese lateralis. 

 The 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 

 ])arts 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 Avhich the body only is visible in the 

 undissected brain, is small and globular. This is what 



