134 U.S. NATIONAL MUSEUM BULLETIN 2 82 



21.22; (g) 2 (19-22) 20.50; (h) 25 (20-25) 22.20; (i) 2 (23-24) 23.50; 

 (j) 29 (20-25) 22.52. 



Total caudal rays: (a) 65 (44-51) 46.14; (b) 25 (43-48) 45.44; (c) 1 

 (47) 47.00; (d) 1 (46) 46.00; (e) 3 (46-47) 46.33; (f) 9 (40-48) 44.78; 

 (g) 2 (41-45) 43.00; (h) 25 (43-50) 46.20; (i) 2 (47-50) 48.50; (j) 29 

 (42-50) 46.28. 



Head length (expressed as thousandths of standard length) : (a) 40 

 (281-333) 306.4; (b) 11 (268-305) 287.0; (c) 1 (279) 279.0; (d) 1 (305) 

 305.0; (e) 2 (279, 304) 291.5; (f) 9 (294-340) 309.1; (g) 2 (275, 293) 

 284.0; (h) 7 (260-277) 271.0; (i) 2 (264, 277) 270.5; (j) 28 (245-293) 

 264.2. 



Soft pectoral rays: (a) 129 (8-10) 8.69; (b) 49 (8-9) 8.76; (c) 2 (8) 

 8.00; (d) 2 (9) 9.00; (e) 4 (9-10) 9.50; (f) 18 (8-9) 8.39; (g) 4 (8-9) 

 8.75; (h) 50 (8-10) 8.96; (i) 4 (8-9) 8.50; (j) 58 (7-9) 8.40. 



Head length: Typical hildebrandi have a relatively large head and the 

 populations from Tennessee have a smaller head. The variation in 

 head size is irregular and difficult to evaluate since the head length 

 appears to be slightly greater in relation to standard length in juveniles. 

 The head lengths plotted against standard lengths (fig. 3) indicate a 

 merging of individuals smaller than 30 mm. in standard length in all 

 populations. Above this size, all specimens from Tennessee show no 

 overlap with those from the Homochitto and Coldwater Rivers. 

 Specimens from Bayou Pierre are somewhat intermediate with a few 

 individuals falling within the plotted area of the Tennessee specimens. 

 The specimen from the Yalobusha system falls within the area of the 



RIVER SYSTEM I 

 HCMOCHITTO 



O HATCHIE i 



. *•• • * . ♦ ° 



■*..■♦• o'oo 



• • ? ■• ,o j^ y 



, * I ■*■ 



o o " o 



o "o 



Standord Length In MM. 



Figure 3. — Head length plotted against standard length, as a comparison of populations 



of NotuTus hildebrandi. 



