| OCR Text |
Show 220 PISCES. body is covered with a smooth skin; the teeth are small and crowded, and at·t·angecl in a. broad crescent b~th above ~nd below; there are seven rays in the branchi::e, and the JaWs and viscera resemble those of a Silurus. M. electricua;-Silurus electricus, L.; Geoff. Po iss. d'Eg. pl. xii, f. 1; Brouss., A cad. des Sc., 1782; the Raasch or Thunder 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 ot 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 with nerves. From tqe Nile and the Senegal. PLATYSTAcus, Bl.(l)-AsPREno, 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 ~n 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) Asrnxno, L., fourth and sixth edit.-Under this name of PLATYSTA.cus, Bloch includes Plotosus and .!J.spredo. Lac6pede 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 SuUims: 1st, the Sil. cornutU8, Forsk., p. 66, on which the genus Macroramplwse, Lac., is founded; it is nothing else than Oentriscus scolopax, L.; 2d, the genus PoGONATUS, Com· mers .. , and Lac. The first species is nothing more than the pogonias, Lac., n, x.vi, 2 and III, p. 138, and consequently of the family of the Scirenre; 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, thoqgh Bloch, Schn., P· 110• very gratuitously arranges it among the Sphyra:nre. MALACOFTERYGII ABDOMINALES. 221 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; th; four of the lower jaw are disposed in pairs, one behind 'the other.( 1) Some of them are found with globules, which appear to be their · eggs, adhering to the thorax by pedicles. LoRICARIA, Lin. So called on account of the angular and hard plates in which the head and body are completely mailed. These fishes are otherwise distinguished from the mailed Siluri, such as the Callichthys and the Doras, by their mouth which opens under the snout. This mouth is most analogous to that of a Synodontis; small intermaxillaries suspended under the snout, and transverse disunited mandibularies, support long, slender, and flexible teeth, terminating in a hook; a broad, circular, membranous veil encircles the opening, and the pharyngeals are furnished with numerous teeth, en pave. The true opercula are immovable, as in Aspredo, but two small, external, movable plates, appear to supply their place. There are four rays in the membrane. Strong spines constitute the first rays of the dorsal, pectorals, and even of the ventrals. They have neither c::eca nor natatory bladder. They may be divided into two subgenera. H YPOSTOMus, Lacep. A second small dorsal furnished with a single ray as in Callichthys; the labial veil simply papillate, and provided with a small cirrus on each side; no plates on the belly; the intestines, spirally convoluted, are as slender as thread, and twelve or fifteen times longer than the body. From the rivers of South America. (2) LoRIOARIA, Lacep. A single dorsal, forward; edges of the labial veil fllrnished with several cirri, and occasionally bristled with villosities; llnder part (l) Silurus aspredo, L.; Platystacus lrevis, Bl., Seb. III, xxix, 9 and 10;-Platys. cotylepl10rus, Bl., 372;-Silurus hexadactylus, Lac., V, p. 82.-TIJe Platystacus verru( )coau.s, Bl. 373, 3, differs from the others in having a shorter anal and tail. . 2 Lc m· can·a plecostomus, L., D., 374;-Hyp. etentaculum, Spix, IV. \ |
