188 FISHES. 



teeth are small and crowded, and arranged in a broad crescent both above 

 and below; there are seven rays in the branchis, and the jaws and vis- 

 cera resemble those of a Silurus. The only species known is that with six 

 cirri, with a head smaller than the body, which, in its anterior part, is 

 swelled out; it is the celebrated fish 



M. electricus; — Silurus electricus, L. ; Silure Electrique du Nil 

 et du Sermjal, Geoff., Poiss. d'Eg. pi. xii, f. 1 ; Brouss., Acad, des 

 Sc. 1782; the Raasch ot Thunder oi the Arabs, which, like the 

 Torpedo and Gymnotus, communicates electric shocks. 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 cellu- 

 lar tissue abundantly furnished with nerves. From the Nile and the 

 Senegal. 



Platystacus*, Bl. — AspREDO, L., in his 4lh andGth editions. 



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, directed backwards, and pro- 

 vided with teeth on the posterior edge only ; and finally and principally, 

 in the fact that they are the only bony fishes known which have no power 

 of motion whatever in their operculum, 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 mem- 

 brane, which has five rays, adhering everywhere else. The lower jaw is 

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

 more strongly dentated than that of any other Silurus; there is but one 

 dorsal on the anterior part of the back, the first ray of which is not very 

 strong; the anal, on the contrary, is very long, and extends under the 

 whole of the tail, which is long and slender. 



But few species are known, and they have six or eight cirri; it is 

 somewhat remarkable, that when the latter number prevails, one pair 

 is attached to the base of those on the maxillaries ; the four of the 

 lower jaw are disposed in pairs, one behind the other'j'. 



• AspREDO, L., fourth and sixth edit.— Under this name of Platystacus, Bloch 

 includes Plotosus and Aspredo. Lacepede leaves the latter with tlie Siluri, but makes 

 » distinct genus of the former. 



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

 SU. cornutus, Forsk., p. 66, on which the genus Macroramphose, Lac, is founded; it 

 is nothing else than Centriscus scohpnx, L.; 2d, the genus Pogonatus, Commers. 

 and Lac. The first species is nothing more than the pogonias, Lac. II, xvi, 2, and 

 III, p. 138, and consequently of the family of the Sciaense; the other, Pogonatus 

 rtara/««, evidently belongs to the genus Umbrina; 3d, i\\e ^enns Centranodon. Lac, 

 or Silurus imberhh, Houttuyn, Ac. Haarl. XX, 2, 338; it cannot possibly be a Silu- 

 rus, 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, very gratuitously arranges it among 

 the Sphyrsenae. 



t miunis aspredo, L.; Platystacus It^vis, B\., Seh. Ill, xxix, 9 and 10; — Platijs. 

 coliilppliortis, Bl. 372; — Silurus he.radactylus, Lac. V, p. 82. — 1\\e' I'latyntacus verntco- 

 sui,, Bl. 373, 3, differs from the others in having a shorter anal and tail. 



