116 



BULLETIN OF THE BUREAU OF FISHERIES 



From an economic point of view, the liner is probably in advance of the other two buffalo 

 fish locally, as its average size is greater and it is more abundant. 



While its diet, as shown by nine specimens examined, resembles somewhat that of the gourd- 

 head, in that it had eaten a moderate amount of the plankton crustaceans, it also had made use of 

 comparatively coarse insects, particularly the abundant water boatman (Corixa) and midge larvse. 

 Possibly in consequence of this coarse diet, the stomach is more muscular, is better developed than 

 in /. cyprinella, and is about twice the size of that of J. bubalus. In comparison with the other two, 

 its intestine is the shortest, being slightly over twice the length of the body, and the intestinal 

 walls are notably thicker. 



Nine specimens taken during the summer were examined for the condition of the gonads; 

 the spawning season evidently was past . In Illinois this species is reported to spawn in the spring 

 (Forbes and Richardson, 1908, p. 72). 



The liner was collected in borrow pits on the Itta Bena Road in Hadley or Allen Lake, in a 

 lagoon near Lake Mclntire, and in a brickyard pond in Greenwood. 



10. Carpiodes difformis Cope 

 River carp 



Carpiodes difformis Cope, Proc, Am. Phil. Soc, Phila., 1870, p. 480. 



We refer 32 specimens, ranging from 35 to 160 millimeters (1% to 6% inches) in length, some- 

 what doutbfully to this species. The body appears to be unusually slender, the depth (in nine 

 specimens 75 to 160 millimeters long) varying from 2.9 to 3.15 in length, and the back is little 



Fig. 2. — Carpiodes difformis, from a specimen from Greenwood, Miss., taken in Pelucia Creek, June 23, 1925 



elevated. The interorbital space is contained 2.55 to 2.8 in head; snout 3.45 to 3.9; tip of lower lip 

 under posterior nostril; scales in lateral line, 36 or 37; dorsal fin notably elevated in front, the 

 longest ray in the large specimens reaching middle of base of dorsal and fully equal to length of 

 head; the number of rays vary from 25 to 27. 



The branchial arches, with their numerous long gill rakers (about 45), almost encircle a bulbous 

 enlargement at the cranial base, constituting an extremely effectual straining apparatus. The 

 relative value of this unique strainer, or selective apparatus, may be gauged by comparing this 

 species with Hybognathus nuchalis, in which the bulbous enlargement is wanting. Although both 

 species ingest the same type of material, the river carp appears to be able to obtain a greater pro- 

 portion of organic material with the inge'sted mud. From an examination of the intestinal contents 

 of four specimens it would appear that over 90 per cent of the ingested material consists of sand 



