NERVOUS SYSTEM. VERTEBRATA. 105 



than in Anguilla. It is remarkable for the large size of 

 its olfactory centres and the linear arrangement of its 

 several parts. It also shows a very decided right-handed 

 rotation of its anterior end. 



The olfactory bulbs are of great size and are separated 

 from the cerebrum by short peduncles. Each receives an 

 immense nerve from the olfactory organ. The right bulb 

 lies partly below the left, much as in the Sole. The basal 

 ganglia of the cerebrum are considerably lobulated, and 

 with the olfactory peduncles can be seen to be covered by 

 a relatively close-fitting pallium. The thalamencephalon is 

 remarkably long for a Teleostean, forming a narrow neck 

 between the cerebrum and the moderately developed optic 

 lobes. The cerebellum is quadrilateral with a marked 

 longitudinal groove on either side. The medulla is small 

 and much concentrated. 



The fish from which this specimen was made measured 

 5 ft. 7 in. in length. 



PLECTOGNATHI. 



D. 119. A Globe Fish (Diodon sp.) opened along the dorsal 

 surface to show the brain and spinal cord. The brain lies 

 in a capacious cranial cavity, and in dorsal view has an 

 outline very similar to the conventional club on a playing 

 card ; this is due mainly to the great development of the 

 optic lobes. The basal ganglia are also large ; each is 

 distinctly divided by a furrow into a lateral and a median 

 lobe. The olfactory bulbs are not shown. The cerebellum 

 is oblong and overhangs the medulla and anterior part of 

 the cord. 



The spinal cord is remarkably short, ending in a fine 

 filament less than 10 mm. behind the posterior border of 

 the cerebellum. The remainder of the neural canal is 

 occupied by a cauda equina, indicated on a level with the 

 pectoral fins by black paper. 0. C. 1308 K. 



DIPNOI. 



. D. 120. Parts of the skull of Ceratodus forsteri with the brain 

 exposed. 



In most characters the brain is very primitive and closely 



