CATFISH GENUS NOTURUS RAFINESQUE 33 



10 to 15, most frequently 11 to 14; precaudal vertebrae 7 to 11, usually 

 8 to 10; ribs 5 to 9, usually 6 to 8; caudal vertebrae showing much 

 variation. The total number of vertebrae often averages higher than 

 in most species of the subgenus Rabida, ranging from 32 to 42. Three 

 species have a modal number of seven (3+4) hypurals; the remainder 

 have six (3+3), as is typical of the other subgenera. The hypurals 

 show various degrees of fusion. The ossified pectoral radials of each 

 side of the pectoral girdle are typically fused; the anal fin is short to 

 relatively long, containing 12 to 27 rays. The number of branched 

 caudal rays is extremely variable; there are usually 16 or more, except 

 in N. leptacanthus, ranging from 14 to 40. The body varies from short 

 to moderately elongate. The species are of variable size : A^^. leptacanthus 

 appears to be a small species; A^. insignis, N. nocturnus, N. phaeus, 

 and N.funebris attain a relatively large size for members of the genus. 



The forms are found both in the lowlands and the mountains of the 

 southern and eastern United States, with gyrinus having the greatest 

 range — into southern Canada and south central Texas. This points to 

 a southeastern origin. At least three of the species, A^". exilis, N. insignis, 

 and A^. gilberti reach their greatest abundance in uplands. Aside from 

 A^. gyrinus, all are typical of graded streams and riffles. N. exilis, 

 N. phaeus, and N. funebris, and possibly AT", leptacanthus, appear to 

 prefer small streams. 



The earliest known species were placed in the genera Silurus 

 Linnaeus or Pimelodus Lac^pede. The name Pimelodon Vaillant was 

 probably derived from the word Pimelodus and was based on Pimelodon 

 insignarius Vaillant equals Noturus insignis (Richardson) ; otherwise 

 it has not been in accepted usage. In later years, most authors have 

 included the species as a unit, together with the species of the sub- 

 genus Rabida, in Schilbeodes, or all \vith fiamis in Noturus. A few 

 that have recognized Rabida as a genus, unnaturally included one 

 or more of the species wjth pectoral spine serrae in that genus and 

 generally restricted Schilbeodes to include only leptacanthus, nocturnus, 

 and gyrinus, all of which lack prominent pectoral spine serrae. 



Aside from Noturus lachneri, which is intermediate in several char- 

 acters between Noturus exilis and Noturus gyrinus, Schilbeodes would 

 be satisfactorily monotypic, with Pimelodon including the remainder 

 of the species. The gradations of characters do not suggest the desir- 

 ability of recognition of one group with a terminal mouth and ten 

 preoperculomandibular pores and another with an inferior mouth. 



Schilbeodes is formed from Schilbe, a genus of fishes lacking an 

 adipose fin, and odes (Greek), meaning likeness. This name was 

 proposed by Bleeker in the belief that the type-species, Silurus gyrinus 

 Mitchill, lacked an adipose fin. 



