220 PISCES. 



body is covered with a smooth skin; the teeth are small and crowded, 

 and arranged in a broad crescent both above and below; there are 

 seven rays in the branchiae, and the jaws and viscera resemble those 

 of a Silurus. 



M. electricus; — Silurus electricus, L. ; Geoff. Poiss. d'Eg. pi. 

 xii, f". 1; Brouss., Acad, des Sc, 1782; the Raasch or Thun- 

 der of the Arabs. The only species known; it has six cirri, and 

 the head is not so big as the body, which is enlarged forwards. 

 This celebrated fish, like the Torpedo and Gymnotus, has the 

 faculty of communicating an electric shock. The seat of this 

 power seems to be in a particular tissue, situated between the 

 skin and the muscles, and presenting the appearance of a fatty 

 cellular tissue abundantly furnished Avith nerves. From the 

 Nile and the Senegal. 



Platystacus, B1.(1) — Aspredo, L. 



These fishes present very singular characters in the flattening of 

 their head and the widening of the anterior portion of their trunk, 

 which chiefly results from that of the bones of the shoulder; in the 

 proportional length of their tail; in their small eyes, placed on the 

 superior surface; in their intermaxillaries under the ethmoid, di- 

 rected backwards and provided with teeth on the posterior edge 

 only; and finally and principally, in the fact that they are the only 

 bony fishes known which have an entirely fixed and immovable oper- 

 culum, a circumstance that is owing to the pieces which should 

 compose it, being soldered to the bone of the tympanum and to the 

 preoperculum. The branchial aperture consists in a simple slit in 

 the skin under the external edge of the head; the membrane, which 

 has five rays, adhering everywhere else. The lower jaw is trans- 

 verse and the snout projected beyond it. The first pectoral ray is 



(1) Aspredo, L., fourth and sixth edit. — Under this name of Platxstacus, 

 Bloch includes Plotosus and Aspredo. Lac^pede leaves the latter with the Siluri, 

 but makes a distinct genus of the former. 



N.B. We must separate from the whole of this great genus Silurus: 1st, the 

 Sil. comutus, Forsk., p. 66, on which the genus Macroramphose, Lac, is founded; 

 it is nothing else than Centriscus scolopux, L.; 2d, the genus Pogonatus, Com- 

 mers.., and Lac. The first species is nothing more than th.e pogonias, Lac, II, 

 XV), 2 and IK, p. 133, and consequently of the family of the Scisense; the other, 

 Pogonatus auratus, evidently belongs to the genus Umbrina; 3d, the genus Cen- 

 tronodon, Lac, or Silurus imberbis, Houttuyn, Act. Haarl., XX, 2, 338; it cannot 

 possibly be a Silurus, as it has scales, spines on the opercula, the first dorsal 

 spinous, &c. It is probably allied to the Perches, though Bloch, Schn., p. 110, 

 verj' gratuitously arranges it among the Sphyrscnse. 



