CENTRAKCHIDJE THE SUNFISHES 233 



ending behind in two flat points or prolonged in a black or partially black 

 flap at the angle; mouth terminal; premaxillaries protractile; maxillary 

 typically with a supplemental bone, which is obsolescent or wanting in some 

 small-mouthed forms; teeth in villiform bands on premaxillaries, lower jaw, 

 and vomer, and usually on palatines; tongue sometimes with teeth; no canine 

 teeth; lower pharyngeal bones separate, with conic or paved teeth; intestinal 

 canal short; pyloric cseca 5 to 10; air-bladder without duct in adult; color- 

 ation usually brilliant; the young more slender than the adults and in most 

 species marked by broad transverse bars. 



Fresh waters of North America; genera about 12, species 

 about 30. Seven genera and 13 species found in the waters 

 of Illinois. 



This family includes the crappies and black bass in addition 

 to the smaller forms more commonly referred to under the name 

 of "sunfishes." The species range in size from the smaller 

 sunfishes, some of which seldom exceed 3^2 inches in length, to 

 the rock bass and the crappie, which reach a weight of more 

 than 1 Ib, and the black bass, the large-mouth form of which 

 occasionally weighs 12 to 14 Ib. 



The typical deep-bodied sunfishes, taken together as a group 

 of species, are about equally frequent in lowland lakes, creeks, 

 and the smaller rivers, and about half as common in upland lakes 

 and in rivers of the larger size, our general coefficients being 

 1.13 for each of the first three situations and .6 and .55 respec- 

 tively for the last two. 



All the family are spring spawners so far as known. Most of 

 the species build nests, which consist of holes scooped out in 

 alluvial, leafy, or sandy bottom about the margins of the waters 

 they inhabit. Sexual differences in form or coloration are not 

 much developed. 



All except the very small species are valued as food, the 

 sunfishes and crappies being among the best of pan-fishes. The 

 output of sunfishes, not including crappie and bass, for the states 

 of the Mississippi Valley in 1899 was 910,963 fe. Of the total, 

 507,680 Ib were furnished by the Illinois River alone. 



The sunfishes proper that is, the Centrarchidce exclusive of 

 the black bass are a well-marked and homogeneous group of 

 species as to form and external structure, but a diverse assem- 

 blage as to ecological relationships. Some of the species, for 

 example, prefer running water, and others quiet; some a clean 

 hard bottom, and others a bottom of mud; some turbid water, 

 and others clear ; some creeks and rivulets, and others the larger 

 rivers. They also form a diverse group in respect to the dis- 



24 P 



