PISCES. 83 



Sisor HAM. BUCHAX. Body naked. Teeth none. First ray of 

 :audal fin produced into a very long seta. 



Sp. Sisor rhdbdophorus. Is this its place ? Compare on this fish F. HAMILTON 

 BUCHANAN, Account of the Fishes found in the Ganges, Edinburgh, 1822, 

 4to. 207 209; J. E. GRAY, Indian Zoology, i. London, 1834, folio, PL 

 84, fig. r. 



B. Mouth terminal or sub-terminal, under the margin of upper 

 aw. 



f Operculum irnmoveable. 



Aspredo L., GROXOV. Body naked, head depressed, with eight 

 r six cirri. Branchial aperture a small fissure. Teeth very small, 

 etaceous, crowded, incurved. Eyes small, superior. Branchioste- 



gous membrane with five rays. Dorsal fin single, small, nuchal; 



anal fin long. First ray of pectoral fins very strong, dentate. 



Sp. Aspredo Icevis VALEXC., Silu.ru* Aspredo L., (Syst. not.), Amcen. Acad. 

 i. Tab. n. fig. v. p. 311, BLOCH Ichth. Tab. 372, fig. i, GUEBIN Iconogr., 

 Poiss. PL 54, fig. i, Cuv. R. Ani. t ed. ill, Poiss. PL 100, fig. i, &c. Fresh- 

 water fishes from Surinam. In many the belly is beset with little stems, to 

 which small round bodies, like eggs, are sometimes attached. 



ft Operculum moveable. (Silurus L. in part.) 



Silivroids proper. The cranium has in the mid plane an oblong 

 aperture or fontanelle in front of the frontal bone between it and the 

 aethmoid, and usually another further back between the frontal bone 

 and the interparietal. The teeth are mostly small, card-shaped, and 

 very numerous, placed close together. The suboperculum is want- 

 ing, and thus the gill-cover consists of three pieces only. The num- 

 ber of branchial rays is very various, but the two hindmost, espe- 

 cially the last, are sometimes much broader than the rest, and supply 

 the place in some degree of the suboperculum. The first ray of 

 the pectoral fin is in many thick and bony, and is so affixed to 

 an angular articular cavity of the humerus, that the extended ray 

 can be rendered immoveable as by a bolt. Mostly a large, strong, 

 cordifonn swimming-bladder is present ; there are no blind append- 

 ages at the inferior aperture of the stomach. 



Many of these fishes live in fresh-water, some as well in rivers as 

 in the sea; but numerous also are the species which, especially in 

 warm regions, must be regarded as marine, the species of Arius and 

 Plotosus in the East Indies, <fec. 



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