120 U.S. NATIONAL MUSEUM BULLETIN 282 



Diagnosis. — Noturus flavus, the only member of the subgenus 

 Noturus, differs from other species of the genus in the increased 

 number of paired fin rays (usually 9 or 10 pelvic and 9 to 11, more 

 often 10, soft pectoral rays), in the backward projections of the lateral 

 edges of the premaxillary tooth band, in the relatively larger size 

 attained, and in always having two free pectoral radials on each side. 

 There are 54 to 67 caudal rays. 



It is distinguished from members of the subgenus Rabida by the 

 reduced serrations of the pectoral spine and by the absence of a 

 mottled pattern, from the subgenus Schilbeodes (except N. gilberti) 

 by the relatively broad cream colored margin of the caudal fin and 

 the immaculate lower surface of the head and abdomen. It differs 

 from N. gilberti in size, in the premaxillary tooth pattern, in the 

 increased number of caudal rays, and in the longer spines. 



Description. — Counts and measurements are given in tables 17 

 to 26. Head depressed; lower jaw included; eye small, 2.5 to 4.7 

 times in snout; humeral process distinct, shorter than width of pec- 

 toral spine; pectoral spine of moderate length, roughened or some- 

 times with a few serrae behind; shallowly beveled or with recurved 

 hooks along the anterior edge, but without anterior dentations as 

 found in Rabida; dorsal spine stout; adipose fin continuous with 

 caudal fin; caudal fin truncate or slightly rounded behind; premaxillary 

 band of teeth with distinct posterior extensions which vary from a 

 shallow V-shape to long, narrow trailing bands that may be nearly 

 as long as the overall breadth of the premaxillary; lower lip and 

 median under surfaces of head covered with coarse papillae. 



In both skeletons and cleared and stained specimens of Noturus 

 flavus: ossified pectoral radials always two and unfused (48 sides); 

 vertebrae anterior to anal origin 14 (in 10) or 15 (4). 



The soft dorsal rays are five (in 2), six (109), and seven (6). In 

 the caudal fin there are (extremes in parentheses): (20) 22 to 26 

 (29), mean 23.9, upper simple rays; (15) 16 to 20 (22), mean 18.2, 

 branched rays of which 7, frequently 8 , are in the upper half and 9 

 to 12 are most usual in the lower half of the fin; (14) 16 to 21 (24), 

 mean 18.1, lower simple rays. There are usually six or seven gUl 

 rakers. 



The size probably exceeds 250 mm. in standard length. Specimens 

 ranging from 175 to 200 mm. are common in collections; many are 

 above 200 mm. The Museum of Zoology has a specimen that is 240 

 mm. in standard length. 



General color in life yellowish, slate-gray, or olive green along sides 

 and on dorsal surfaces. In preservative, top of head, areas about 

 dorsal fin base, and between dorsal and adipose fins dark gray; ven- 

 tral surface immaculate, including mental barbels, lower side of head, 



