CATFISH GENUS NOTURUS RAFINESQUE 71 



notch is formed at their juncture; upper procurrent caudal rays 

 moderate in length; caudal fin truncate or slightly rounded behind. 



There are usually 6 soft dorsal rays; in 111 specimens, there are 

 five (in 2), six (108), and seven (1). There are five to eight gill rakers 

 on the first arch. The largest specimen examined is 78.7 mm. in 

 standard length. There are (extremes in parentheses) : (17) 17 to 20 

 (23), mean 19.2, upper simple caudal rays; (14) 15 to 18 (19), mean 

 16.7, branched caudal rays, of which 7 are usually in the upper one- 

 half of the fin and 9 or 10 are most frequent in the lower one-half; 

 and (12) 14 to 17 (20), mean 15.6, lower simple caudal rays. 



In 13 stained specimens vertebrae anterior to the origin of the anal 

 fin eleven (in 7), twelve (5), and one not counted; ossified pectoral 

 radials fused on all 26 sides. 



The general life color is reddish brown or a dark yellowish brown. 

 The pigmentation in preserved material is as follows: top of head 

 dark brown; side of body and dorsal surface uniform with slight 

 darkening at the base of the dorsal and adipose fins; area over air 

 bladder frequently dark gray; lower cheek and side of head pale yellow- 

 ish; upper barbels light tipped, mostly pigmented only at their base; 

 anterior naris pale; lower surface of head, abdomen, and pelvic fin 

 creamy white, almost immaculate, but each with scattered pigment, 

 especially concentrated in front of mental barbels; anal and dorsal 

 fins light with moderate, scattered pigment; pectoral fin with 

 pigment concentrated near base, scattered elsewhere; caudal and 

 adipose fins sometimes with a light margin, darkly blotched \\dth large 

 gray-black chromatophores which often diffuse throughout the fins; 

 large brownish chromatophores scattered over fins, head, and side; 

 mental barbels usually immaculate except at base. 



Variation. — Table 7 gives variation in the number of pelvic and 

 soft pectoral rays. Counts from one or more, usually several, collec- 

 tions from each river system are combined; enumerations were usually 

 made of rays of both fin pairs of the same specimens, and both sides 

 are tabulated individually. The pelvic rays are rather uniformly 

 eight, but there is a strong increase in pectoral rays from west to east. 

 No correlation between pelvic and pectoral ray counts is indicated. 

 The increase in pectoral rays is a moderately uniform gradient, but 

 certain modes are evident. West of the Pascagoula River system, the 

 modal number of rays is eight. From the Tombigbee and Alabama 

 River systems eastward, the mode is nine. 



There are normally eleven preoperculomandibular pores throughout 

 most or the range. However, 19 of 22 canals tabulated from the 

 Comite River system (the western edge of the known range), south- 

 western Mississippi, have ten pores, and only three sides have eleven 



