26 



ee. Breadth of Interorbltal space less than diameter of eye. 



f. Body not extremely elongate and not hyaline. 



e. Mouth more or less oblique, terminal; head rather pointed; belly with enlarged 

 scales or a naked strip. 



h. Premaxillary broadly joined to skin of forehead, free only at sides. 



Hadeopterus. 



hh. Premaxillary separated from skin of forehead by a groove, which is some- 

 times crossed by a narrow frenum Cottogastkr. 



gg. Mouth inferior, horizontal; profile much decurved. 



i. Anal spines 2, well developed; ventral fins close together, an enlarged scale 

 between their bases Di plesion". 



11. Anal spine 1, weak; ventrals separated by a space equal to width of base. 



BOLEOSOUA. 



ff. Body extremely elongate; hyaline in life. 



j. Body very pale, marked with rows of black spots; very slendei, cylindrical; 

 premaxillary protractile Ammockypta. 



jj. Body mottled with dark above and with black spots on sides; terete; head de- 

 pressed; snout long; premaxillary not protractile Crtstallaria. 



dd. Body compressed (or cylindrical); skull just behind eyes fl-sbaped in cross- 

 section; premaxillary never protractile; belly covered with ordinary scales. 



k. Lateral line straight; body rather stout; caudal peduncle not noticeably long 

 and slender; head usually more or less pointed; month nearly or quite 

 terminal Etheostoma. 



kk. Lateral line arched, parallel with line of back; caudal peduncle slender: profile 

 much decurved; mouth inferior Boleichthts. 



cc. Lateral line wanting Micbopkeca. 



Stizostedion vitreum (Mitehill). — Wall-eyed Pike: Jack Salmon. 



A well known fish, of large size, with fusiform body; well developed canine teeth on the 

 jaws and palatine bones, as in the next species; a large jet-black spot on the posterior two 

 membranes of the spinous dorsal. 



Common in the Illinois basin and in the northwestern portion of the State. Taken once 

 from the Kaskaskia River at Vandalia, and in large numbers from the Wabash above 

 Mt. Carmel. 



Stizostedion canadense (Smith). — Sanger; Sand Pike. 



Spinous dorsal with two or three rows of round blaek spots, but without a black blotch 

 on the posterior rays; second dorsal with three irregular rows of round dark spots. 



We have specimens from the Rock River at Dixon, from lakes about Quincy. and from the 

 Illinois River at Pekin. Reported from other places northward. Less common than the 

 preceding species. 



Perca flavescens (Mitehill). — Yellow Perch; Ringed Perch. 



A very common lake fish, found also in streams. Much sought by the pot-flsherman; may 

 often be caught on a hook baited with a piece of red flannel; the individuals of a school will 

 usually bite until the last one is taken. The flesh is of fine flavor when fried. 



Common in Lake Michigan, and in the small elaclal lakes. Also common in the Illinois 

 River at Ottawa, Peoria, Havana, and Meredosia, and in lakes about Quincy. 



Percina caprodes (Rafinesque). — Log Perch; Hog Perch; Giant Darter. 

 (337) 



A fish well known to boys and often caught by them on pin-hooks, "along with 'red-eyes' 

 'stone-toters,' 'horny-heads.' and other 'boys' fish.' " Its large size, cyliMdrical form, yel- 

 lowish color, with narrow black bars, and its pig-like snout will serve to distinguish it from 

 other darters. 



Occurs infrequently in the south half of the State. Frequently taken northward in gravelly 

 situations. 



KEY TO ILLINOIS SPECIES OF THE GENUS IIADROPTKRCS. 



a. Head pointed; lower jaw projecting: colors never very dark: a row of black spots 

 on sides; a brilliant red or orange band on membranes of spinous dorsal. 



H. PHOXO0EPHALU8. 



aa. Bead more obtuse; lower jaw included, but mouth terminal; much dark colora- 

 tion on sides. 



b. Gill membranes either connected or not connected across the isthmus, the 



connection, if present, not exceeding In width the diameter of the eye; border 

 of preopercle not serrate. 



c. Dorsal spines 13 to 15 H. aspeo. 



