38 MARINE AND FISHERIES 



5 GEORGE v., A. 1915 



River, but enormous numbers of the young fish of scarcely more than 10 mm. in 

 length are commonly to be found swimming in large schools outside of the main 

 shore, either in the vicinity of the reefs or in the deep water. It is a lithe, active 

 species, and when feeding in schools, especially towards sundown, is often seen 

 jumping out of the water, presumably in the act of taking insects from the surface. 



Length of the largest specimens 3 inches; commonly much smaller. Body 

 very slender, little compressed, the depth 7 to 7 • 7 in the length. Head 4 • 4 to 4 • 8, 

 terminating in a blunt but beak-like snout. Jaws rather narrow, and when viewed 

 from the side bowed upwards in their middle portions. General coloration olive, 

 the body translucent, and allowing the air-bladder and vertebral column to show 

 through the muscles. Dorsal surface with a dark vertebral streak and with 

 fine dark edgings on the minute scales. Sides with a silvery band, more or less 

 imderlaid by a dark line which broadens into a band on the posterior part of the 

 body. 



Dorsal fins two, the anterior consisting of 4, rarely 3, weak spines, the posterior 

 of 12 (sometimes 11 or 13) ordinary rays. Anal fin very long, its posterior portion 

 shallow, with 25 to 28 rays (the number reported by Forbes and Richardson ('08) 

 for Illinois is 22 to 25). Scales very small and rounded, about 95 in a longitudinal 

 row. 



The food consists of minute plankton entomostraca, together with small 

 insects, the latter including terrestrial forms which are evidently taken from the 

 surface of the water. 



Family centrarchidae. 



(Basses and Sunfishes) 



This family is represented by three genera and four species, probably the most 

 familiar of all fishes inhabiting the region, and one of them, the small-mouthed 

 bass, important as its chief game fish. 



The three genera are separable as follows: 



a. Base of the dorsal fin less than twice as long as that of the anal, the latter contained 

 about 1.5 Ambloplites 



aa. Base of the dorsal fin more than twice as long as that of the anal 



b. Body very short and deep, the depth 2.2 to 2.4 Eupomotis 



bb. Body more elongated, the depth at least 2.9 and usually 3.5 Micropterus 



Genus Ambloplites. 



Ambloplites rupestris, Rafinesque. 



(Rock-bass) 



Extremely abundant in all situations along the main shore, in the larger in- 

 land lakes in the vicinity of Go Home Bay, and in the Musquash River, though not 



