122 U.S. NATIONAL MUSEUM BULLETIN 282 



dorsal rays; 6 + 12 = 18 anal rays; 24 + 8+12 + 18=62 caudal rays; 

 1 epural; 3 + 3 = 6 hypurals, all free distally; 39 vertebrae of which 

 14 are anterior to the origin of the anal fin; 10 soft pectoral rays 

 on the left side and 11, including a tiny inner ray, on the right side. 

 On each side there are 10 pelvic rays, 2 internasal pores, and 11 

 preoperculomandibular pores. The head length is stepped into the 

 standard length 3.7 times, the eye into the snout 3.2 times, and the 

 distance from tjie rear end of the adipose fin to the tip of the caudal 

 fin into the distance from the origin of the dorsal fin to the rear end 

 of the adipose fin 1.8 times. Further measurements are given in 

 table 27. 



Variation. — The following summary of the data obtained on this 

 species is tJie result of combining several samples from various geo- 

 graphic areas. It indicates relatively little geographic variation. The 

 data listed consist of the number of counts, range (in parentheses), 

 and the mean for, in sequence: (a) Missouri River, South Dakota 

 and Nebraska, (b) Neosho and Illinois Rivers of Kansas and Okla- 

 homa, (c) Osage River system, Missouri, (d) Missouri and Mississippi 

 Rivers, Missouri, (e) Ohio and Cumberland Valleys, (f) Great Lakes 

 basin, chiefly Huron River, Michigan, and (g) totals. 



Soft pectoral rays: (a) 68 (9-11) 9.68; (b) 40 (9-11) 9.98; (c) 5 

 (9-10) 9.60; (d) 52 (9-11) 9.62; (e) 40 (9-11) 9.80; (f) 79 (9-11) 9.85; 

 (g) 284 (9-11) 9.77. 



Pelvic rays: (a) 68 (8-10) 9.29; (b) 40 (9-10) 9.18; (c) 9 (9-10) 

 9.11; (d) 51 (8-10) 9.31; (e) 40 (8-10) 9.40; (f) 80 (8-10) 9.25; (g) 288 

 (8-10) 9.28. 



Anal rays: (a) 28 (15-18) 16.18; (b) 17 (15-17) 15.88; (c) 5 (16-17) 

 16.60; (d) 26 (15-18) 16.38; (e) 19 (15-19) 17.11; (f) 37 (16-18) 17.27; 

 (g) 132 (15-19) 16.64. 



Lower-half caudal rays: (a) 19 (26-30) 28.16; (b) 20 (28-32) 29.75; 

 (c) 5 (27-30) 28.60; (d) 26 (27-33) 30.08; (e) 18 (27-31) 29.28; (f) 36 

 (26-32) 28.67; (g) 124 (26-33) 29.15. 



Upper-half caudal rays: (a) 19 (29-36) 31.89; (b) 20 (30-33) 31.00; 

 (c) 5 (30-33) 31.40; (d) 26 (27-34) 31.61; (e) 18 (29-32) 30.78; (f) 36 

 (28-33) 30.75; (g) 124 (27-36) 31.11. 



Total caudal rays: (a) 19 (55-66) 60.05; (b) 20 (58-64) 60.75; 

 (c) 3 (60-63) 61.33; (d) 26 (55-67) 61.38; (e) 18 (57-63) 60.06; (f) 37 

 (54-64) 59.27; (g) 123 (54-67) 60.24. 



Vertebrae: Specimens from the southwestern portion of the range, 

 lower Missouri and Arkansas River drainages, appear to have fewer 

 vertebrae with modal numbers of 38 or 39; those from the upper 

 Missouri have slightly more, and those from elsewhere the most, 

 modally 39 or 40; French Cr., Pennsylvania 16 (38-40) 39.38; Ten- 

 nessee R. system 25 (38-41) 39.80; Great Lakes drainage 44 (38-41) 



