318 FISHES OF 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 Entomostraca, 

 but with young specimens of amphipod crustaceans also. The re- 

 maining two thirds was essentially all Chironomus larvae, with only 

 a trace of small larvae of May-flies. 



Family SERRANID^ 

 (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 osse- 

 ous; vertebras typically 10 -1-14 =24* never more than 35; anterior ver- 

 tebrae without transverse processes; ventrals thoracic, usually I, 5; dor- 

 sals 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; branchiostegals 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 usu- 

 ally ending in 1 or 2 flat spine-like points ; mouth not much oblique ; pre- 

 maxillary 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; intes- 

 tine short; stomach caecal, 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^ 



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 

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

 toothless Morone. 



