30 A Guide to the Zoological Collections 



abdominal cavity on either side of the vertebral column 

 and their ducts open into the cloaca. In the dissections 

 of Pristipoma and Lates (Teleostean type) they adhere 

 to the backbone and open behind the vent. 



The Nervous System of Fishes, portions of which 

 are illustrated by labelled dissections of an Indian 

 Carp, of a Bekti, of Lamprogrammus and of a Shark, in 

 Case ii, corresponds with that of higher vertebrates. 



The Brain is small and is divided into five regions 

 none of which conceal any of the others in the Carp 

 and Lamprogrammus, though some of them do in the 

 Shark. The five regions are (i) the paired olfactory 

 lobes which are relatively large, (they have been re- 

 moved in Lamprogrammus to show the crossing of the 

 optic nerves) ; (2) the paired cerebral hemispheres, which 

 are small, though larger in the Shark than in the 

 others; (3) the paired optic lobes, which in the Carp and 

 Lamprogrammus are the largest lobes of the brain, 

 though in the Shark they are small and are completely 

 hidden by the cerebellum ; (4) the unpaired cerebellum 

 which is small in the Carp, but large in the Shark ; (5) 

 the medulla oblongata, which is continued without a 

 break into the spinal cord. 



Immediately behind the cerebellum there is seen, in 

 a dorsal view, a hollow or groove, called the fourth 

 ventricle : this can be folloived forwards into the brain 

 and backwards into the spinal cord, betokening the 

 tubular origin of the central nervous system. 



The olfactory lobes are prolonged to form the so- 

 called olfactory nerves, which expand where they meet 

 the olfactory sacks : observe the large size of these sacks 



