ENOEPHALON OF FISHES. 



275 



Herring, fig. 1 84, c ; but sometimes covering only a small portion, as 

 in the Chub, fig. 177, c, the Lumi)-fish, and the Lepidosteus, fig. 

 174, c. The relative size of the cerebellum, accordingly, varies 



^-•■•-1'i.j-- 



175 



Brain ; 



Lei.>ldosteus 



BraiQ; Amblj'opsi3 

 magnllled 



Brain ; Eel. CCii. 



greatly In difFcreiit bony fishes ; it is very small in tlie lazy Lnmp- 

 fish, and extremely large in the active and "\varm-l:>h)oded Tunny, 

 where, also, its surface shows transverse j^-roovings. 

 The cerebellum is unsymmetrically placed in the 

 Pike and some Flat-fish {Plevronectida), and is 

 unsymmetrically shaped in the Sharks : it presents 

 a longitudinal groove in the Diodon, and a pos- 

 terior notch in the Herrino- : a transverse notch di- 

 vides it into an anterior and posterior lobe in the 

 Lophius : it bears a crucial depression in the Skate. 

 The cerebellum presents in many fishes a small 

 cavity or fossa at its under part, continued from 

 the fourth ventricle, fig. 178, c: it is solid in the 

 Tench, the Garpike, and the common Eel : some 

 grey matter is usually found in its interior, with 

 feeble indications of vphite stria3 ; but there is no 

 ' arbor vitas,' except in the Tunny and Sharks. 



The posterior ' crura cerebelli ' are formed by 

 the posterior pyramids, fig. 172, d, with part of the restlform 

 tracts, ib. c ; vertical fibres from the sides of the cerebellum 

 continue to attach it to the 

 sides of the restiform or trige- 

 minal lobes, and some of these 

 are continued as arciform fila- 

 ments upon the under surface 

 of the medulla oblongata : they 

 answer to the ' crura cerebelli ad j)ontem ' of Mammalia ; but, as 



T 2 



]Jra1n and portion of 

 spinal marrow of 

 Cliub {LcitclHcus) 



Scctiou of Biaiii, Carp 



