132 NORTHERN ZOOLOGY. 



SILUROIDE^. 



This family is distinguished from the others of the same order by the skin being 

 either naked, or protected by large bony plates, but always destitute of true scales. 

 The intermaxillaries, suspended under the ethmoid bone, form the border of the 

 upper jaw, while the labials are lengthened out into barbels, or are simply rudi- 

 mentary. The intestinal canal is wide, without cseca, and doubles upon itself; 

 the air-bladder is large, and adheres to a peculiar bony apparatus ; the dorsal and 

 pectorals have almost always a strong spine, with a joint for their first ray, and 

 there is very often an adipose fin as in the Salmonoideae. The family contains four 

 genera, Silurus, Malapterurus, Aspredo, and Loricaria, the first of which, being 

 by far the most extensive, is divided into twelve sub-genera. The species abound 

 in the rivers of warm countries and are numerous in America. The following 

 species have been detected in the United States. Bagrus marinus, Pimelodus 

 catus, albidus, nebuhsus, ceneus, cauda-furcata, nigricans, natalis, and insigne 

 (livree, Le Sueur). Doras costatus, Callichthys {Silurus callichthys, Linn.) and 

 Aspredo (S. aspredo, Linn.). The Mysti, Hypostomes, and Loricarice, are South 

 American fish. The Schilbes, Synodontes, Heterobranchi, and Malapteruri, are 

 inhabitants of the Nile, Senegal, and some Asiatic rivers. The Plotoses are Indian 

 fish. The Silurus glanis is the largest fresh-water fish that exists in Europe, being 

 sometimes upwards of six feet long, and weighing three hundred weight. 



[58.] 1. Silurus (Pimelodus) cosnosus. (Richardson.) Huron 



Pimelode. 



Family, Siluroideas. Genus, Silurus. L. Sub-gemts, Pimelodus. Lacep., Cuv. 



Fish belonging to the genus Silurus have the mouth at the extremity of the 

 snout ; and in most of the sub-genera the first ray of the pectoral fins is a strong 

 spine, articulated in such a manner to the shoulder-bone, that the fish can at plea- 

 sure lay it along the body, or fix it perpendicularly, so as to render it capable of 

 inflicting a very dangerous wound. The head is depressed, the intermaxillaries 



