30 Synopsis of the Fresh Water Fishes, 



numerous species with which it has little affinity, is almost 

 exclusively confined to the North American continent. The 

 Asiatic species, which have been referred by M. Valenciennes 

 to his first section of Pimelodus, appear to form a distinct 

 genus, but are only known by imperfect and very unsatisfactory 

 descriptions, and most of them have never been seen by 

 naturalists, the descriptions having been drawn up simply from 

 inspection of Chinese figures. One of these Asiatic species, which 

 has long been known by a brief description and figure given by 

 Russel in his "History of Aleppo," and which has received 

 from Linnaeus, the name of Silurus cous, proves not to belong 

 to the genus. Valenciennes, who had only the work of Enssel 

 as original authority, referred it to Pimelodus with doubt. 

 The species has recently been re-discovered, and has been 

 placed by Mr. Heckel in the genus Arius, in his memoir on the 

 Syrian Fish, obtained by Russegger. There have been still 

 further separated from Pimelodus, the !N^oturus of Rafinesque, 

 which is confined to North America, the Calophysus of 

 Miiller and Troschel, peculiar to South America, and the 

 Asiatic genus, Bagarius of Bleeker. The Tachisunis of Lace- 

 pede, will also probably be found, when properly restricted, 

 to be an exclusively Asiatic genus. 



The genus which we have now called Pimelenotus, and which 

 "we believe we have been the first to recognise, is, with the ex- 

 ception of a single species, peculiar to South America and its 

 zoological dependencies. In the number of its species it appears 

 to hold that station in South America, which is possessed by the 

 natural genus Pimelodus in North America ; it embraces many 

 of the species described by M. Valenciennes in the " Histoire 

 Naturelle des Poissons," and by Drs. Miiller and Troschel in 

 their " Horse Ichthyologicse," and in Schomburgh's " Reisen." 

 The P. Sebae, P. pati, P. sapo, P. Hilarii, P. gracilis, and P. 

 Pentlandii, which were first described by M. Valenciennes, are 

 some of the species that appear to belong to the "new genus," 

 but P. pati and the allied species are doubtful. The species 



