90 PHYSIOLOGICAL SERIES. 



cephalon. The dorsal and lateral parts of the thalamen- 

 cephalon are much restricted, being buried to a considerable 

 extent by the optic lobes ; but the hypothalamus is strongly 



lopr.l, tin- lobi int'eriores in particular being large and 

 prominent: they lie almost directly below the optic lobes. 

 The latter are of great size, of almost globular form, and 

 are separated in the mid-line by a sharp furrow. The 

 optic tracts arise mainly from their superficial parts, and 

 forward on either side of the thalamus to the ventral 

 Mirlace of the cerebrum ; here they leave the brain and 



the right below the left to form the optic nerves. 



The cerebellum is tongue-shaped with its free end over- 

 hanging the rhomboid fossa. It is connected with the basal 

 parts of the brain by a pair of prominent anterior crura 

 that give passage to the cerebellar tracts and contain the 

 nuclei of part of the trigemino-facial nerve complex. The 

 medulla, in comparison with that of a Shark, is much 

 concentrated. The rhomboid fossa is consequently small. 

 Its borders show definite swellings, due to the posterior 

 crura of the cerebellum and to the nuclei of the posterior 

 cranial nerves. 



D. 88. Parts of the head of a Cod (Gculus morrhua) with the brain 

 exposed from the lower surface. The optic nerves, before 

 entering the brain, cross one another, the left beneath the 

 right. Behind this crossing lies the largo spherical pituitary 

 body attached to the antero-ventral surface of the infun- 

 dibuluin. It covers the anterior parts of the lobi inferiores., 

 P.. hind it in the mid-line, separating the posterior parts of 

 the lohi int'eriores, is a small saccus vasculosus continuous 

 with the distal end of the inftmdibulum. 



In ihi- -perim. n th<- distribution of the third pair of 

 cranial nerves i- >hown. It send.- branches to the inferior, 

 Ulterior, and internal recti and to the inferior oblique, as 

 well as a ciliary branch to the eyeball. A bristle is placed 

 beneath the branch to tin- inferior oblique. 



0. (!. 1380 A. 8. 



D. 89. A sagittal section of the cranium and brain of a Cod (Gadus 



i rfiua). J>l:ick paper, in-eried behind the pallium, brings 



iMit dearly the relation.- of this membrane to the basil 



