318 FISHES OP ILLINOIS 



This little darter inhabits generally small streams and ponds 

 of the Great Lake region, and ranges thence southwest to 

 Arkansas. 



Nine specimens from four localities in northern Illinois had 

 made two thirds of their food from Crustacea, mostly Entomos- 

 traca, but with young specimens of amphipod crustaceans also. 

 The remaining two thirds was essentially all Chironomus larvae, 

 with only a trace of small larvae of May-flies. 



FAMILY SERRANID4E 



THE SEA BASS 



Body oblong, more or less compressed; dorsal and ventral outlines usually 

 not perfectly corresponding; scales adherent, usually but not always ctenoid; 

 lateral line present, not extending on caudal fin; skeleton osseous; vertebrae 

 typically 10 + 14 = 24, never more than 35; anterior vertebrae without 

 transverse processes; ventrals thoracic, usually I, 5; dorsals confluent or not, 

 the spines 2 to 15 in number; anal spines, if present, always 3; caudal variously 

 formed; no mesocoracoid; gill-membranes separate, free from isthmus; 

 branchiostegels normally 7, occasionally 6; pseudobranchiae present, large; 

 gill-rakers long or short, usually stiff and armed with teeth; preopercle usually 

 more or less serrate; opercles usually ending in 1 or 2 flat spine-like points; 

 mouth not much oblique; premaxillary protractile; supplemental maxillary 

 present or absent; teeth conical or pointed, in bands on jaws, vomer, and 

 palatines; no canines; lower pharyngeals separate (except rarely), with pointed 

 teeth; intestine short; stomach csecal, with few or many pyloric appendages; 

 air-bladder present, usually small and adherent to wall of abdomen. 



Carnivorous fishes, chiefly marine, found in all warm seas; 

 a few genera found in fresh water, 2 in the Mississippi Valley; 

 genera known about 60 to 70, species about 400. Many of the 

 species are of great value for food and game qualities. 



KEY TO ILLINOIS GENERA OF SERRANID^E 



a. Dorsal fins separate; anal fin III, 11 to 13, the spines graduated, the first 

 about half length of second, and second distinctly shorter than third; 



lower jaw projecting; base of tongue with teeth Roccus. 



aa. Dorsal fins joined; anal fin III, 10, the spines not graduated, first scarcely 

 % of second, second and third subequal; jaws almost equal; base of tongue 

 toothless Morone. 



