39 



the dorsal covering of the caudal peduncle. Belly wholly naked 

 in front of ventrals ; breast with a few bony points similar to 

 those on the lower part of the sides. The pectoral shields are 

 long and narrow (PI. V.), the triangular, posterior part equal- 

 ing in area the remainder of the shield. 



Rostrum long and narrow (PI. V.), 2.5 to 2.9 in length of 

 head ; the eye very small, 8.3 to 10 in the interorbital s\K\n>. 

 which is 3.7 to 4.2 in the length of the head. Barbels doubly 

 pectinated on the anterior edge, the posterior pectinations ob- 

 solete or wanting, the inner barbels 1.7 to 2.9 in length of 

 outer. Mouth large, 1.4 to 1.6 in the greatest width of the ros- 

 trum. Papilla^ of the four clusters on the lower lip reduced to 

 a few 7 flattened scallops at the hinder edge of the lappet. 



Gill-membranes united to the isthmus and to each other 

 in a deep angle (PI. V.), and continued backward to cover the 

 anterior fourth of the pectoral shields. Operculum long and 

 narrow, its depth contained more than twice in distance from 

 posterior margin of cheek to posterior margin of gill-opening, 

 and this distance about 8.5 times in length of head and body. 

 Gill-rakers 10 or 11, + 3, the two rows of each arch separated by 

 a broad smooth surface (PI. VII.). 



Dorsal fin of 35 to 43 rays, the length of its base 11.8 to 

 12.8 in length of head and body; anal rays 20 to 23, ventral 

 rays 23 to 26. 



Length of our seven specimens 19 to 43 inches, to base of 

 caudal fin, the largest weighing 9.75 pounds. Mr. Ashlock has 

 seen specimens 4.5 feet long, with an estimated weight of 16 

 pounds. 



Described from 9 specimens. 



The sexual differences are not known, all our specimens 

 being males. The species is said by Mr. Ashlock to spawn 

 between March and June, and to continue spawning sometimes 

 as late as August. The testes were well developed in those 

 taken about the middle of June. 



Although seen by us only from the Mississippi River at 

 Grafton, this fish is said by Mr. Ashlock to be more abundant 

 along the lower Missouri. Catches of sturgeon were seen by 



