288 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM, 



is coutaiued 3^ times in length of body. The length of the first anal 

 ray (.01) is contained 8 times in the least height of taU. The ninth and 

 longest anal ray (.077) is nearly as long as the base of the first dorsal 

 (.08). The length of the last anal ray (.033) equals J that of the middle 

 caudal rays (.066), which is contained 15 times in the length of body. 



The proportion between the middle and external caudal rays (.14) is 

 as 3|- to 8, both being measured from the middle of the origin of the 

 middle caudal rays. The length of the external caudal rays is contained 

 7 times, and of the middle caudal rays, 15 times in the length of body. 



The distance of the pectoral from the snout (.26) is somewhat more 

 than twice the length of the pectoral (.125). 



The distance of the ventral from the snout (.56) equals 4 times the 

 length of the external caudal rays. The length of the ventral equals ^ 

 of the length of the head and -^ of the length of body. 



Radial formula: B. VIII; D. II, 6; A. Ill, 32; P. I, 11; Y. I, 7. 



Color: — Upper part of body and head bluish slate; lower parts 

 whitish. 



The length of the ovaries is 17 inches, and the weight 5 pounds avoir- 

 dupois. The diameter of the eggs is from ^ to -jV of an inch. They 

 are not readily separable and are apparently far from maturity. 



Amiurus ponderosus differs considerably from A. nigricans as will be 

 seen in the measurement tables. A. ponderosus has(l) a deeper body; 

 (2) a much wider mouth ; (3) a wider interorbital space ; (4) the inter- 

 maxillary and the intermaxillary band of teeth longer ; (5) the maxillary 

 barbel only § as long as the head instead of f as in nigricans; (6) the 

 long diameter of the eye contained 17^ times in the length of the head 

 instead of 9 to 11 as in nigricans; (7) the first ray of the dorsal less 

 than ^ as long as the head ; (8) the longest anal ray less than ^ as long 

 as the head ; (9) the caudal rays shorter and the caudal not forked ; (10) 

 the pectoral considerably less than ^ as long as the head (more than ^ 

 in A. nigricans); (11) the ventral contained 3 times in length of head 

 (2^ in A. nigricans); (12) anal rays, III, 32. 



