CLASS PISCES. 533 



effects extends all along the under part of the tail, 

 half the thickness of which it nearly occupies. It 

 is divided into four longitudinal fasciculi, two large 

 ones above, two small ones underneath, placed against 

 the base of the anal fin ; each fasciculus is composed 

 of a great number of membranous parallel laminae, 

 very much approaching to each other, and pretty 

 nearly horizontal, leading on one side to the skin, and 

 on the other to the middle vertical plane of the fish ; 

 finally, they are united one to the other by an infinity 

 of small vertical plates, directed transversely. The 

 small cells, or rather the little prismatic and trans- 

 verse canals, intercepted by these two orders of la- 

 minae, are filled with a gelatinous matter, and the 

 whole apparatus receives proportionally an abundance 

 of nerves \ 



Carapus a , Cuv., 



Have the body compressed and scaly, and the tail 

 attenuated very much behind. They also live in the 

 rivers of South America 3 . 



1 See Hunter, Phil. Trans. Vol. LXV. p. 395. Add the Gym- 

 notus cequilabiatus, Humb. Obs. Zool. I. pi. x. No. 2. It would 

 appear, according to M. de Humboldt, that this species has no pos- 

 terior air-bladder. 



2 Carapo, the name of these fishes in Brazil, according to 

 Marcgrave. 



3 Gymnotus macrourus, Bl. 157. 2. Carapo, Gmel. G.brachiurus, 

 Bl. 157. 1. -fasciatus, Gmel. G. albas, Seb. III. pi. xxxii. 

 f. 3. 



