270 



ANIMAL PHYSIOLOGY. 



[LESSON 83. 



LESSON LXXXIII. 



NERVOUS SYSTEM IN FISHES, CONCLUDED. 



1211. In the Trigla lyra (Fig. 384), where the pectoral fins are 

 of great size, a series of ganglionic enlargements (5, b) of the spinal 

 chord (a) are observed at its upper part, which corresponds in num- 

 ber with the number of the large detached rays of the pectoral fins 

 presented by the different species, Trigla cucullus having five en- 

 largements and five detached rays, and the Trigla lyra having six 

 of each. 



1212. The demonstration of the figure is as follows : The spinal 

 chord is seen at a. The medulla oblongata which consists of six 

 ganglionic enlargements at b, b. At c, d, the cerebellum is seen, and the 

 cerebrum aty. In this superior portion of the brain, the optic lobes 

 (e, e), the olfactory lobes (g), and the olfactory nerves (h) are found. 



FlG . 384. FlG . 385> 1213. The posterior extremi- 



ty of the spinal chord is some- 

 times sensibly enlarged where 

 nerves proceed to the muscles of 

 a large caudal (tail) fin, and in 

 abdominal fishes (an order so 

 called from the attachment of the 

 ventral fins to the abdomen, be- 

 hind the pectorals, or chest fins), 

 an enlargement is observed, cor- 

 responding with the ventral, or 

 belly fins. 



1214. In front of the medulla 

 Brain, Conger eel. oblongata and cerebellum in os- 

 seous fishes, there are three pairs 

 of rounded lobes placed in front of ach other along the floor of the 

 cranium, and occupying but a small portion of that capacious cavity, 

 as seen in the brain of the Conger eel (Murcsna conger, Fig. 385), 

 where these three pairs of lobes are nearly equally developed and 

 similar in form. 



1215. The spinal chord is shown at a; to this succeeds the 

 cerebellum (b). The cerebrum is marked e, containing the optic 

 lobes (c), the olfactory lobes (/), the olfactory nerves (g,g), and the 

 pineal gland (d). 



1216. The posterior pair of lobes (c), immediately before the 



Nervous system, 

 Trigla lyra. 



