70 



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

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



crossed Ijy a narrow freniini Cottogastek. 



gfi. Month inferior, liorizontal; profile much decurved. 



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

 tween their bases Diplesion. 



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



BOLEOSO.MA. 



ff. Body extremely elongate; hyaline in life. 



j. Body very pale, marked with rows of black spots; very slender, cylindrical; pre- 

 maxillary ijrotractile Ammocr ypta, 



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

 pressed; snout long; premaxillary not protractde CrYsTALLARIA. 



dd. Body compressed (or cylindrical); skull just behind ^yes n-shaped in cross- 

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

 k. Lateral line straiglit; body rather stout; caudal pertuncle not noticeably long and 

 slender; head usually more or less pointed; mouth nearly or quite terrninal. 



Etheosto.ma. 

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



much decurved; mouth inferior BOLEICHTHYS. 



cc. Lateral line wanting Microperca. 



Stizostedion vltreiuii (Mitchill) — 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 Wabasb alKjve Mt. 

 Carmel. 



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



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

 the posterior ra\ s; second dorsal with three irregular rows of round dark spots. 



VVe have specimens from the Kock river at Dixon, from lakes about (juincy, and from 

 the Illinois river at Pekin. Reported from other places northward. Less common fhan the 

 preceding species. 



Perca pavescens (Mitchill). — Yellow Perch; Ringed Perch. 



A very common lake hsh. found also in streams. Much sought by the pot- fisherman; 

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

 will usually bite until tlie last one is taken. The flesh is of fine flavor when frieii. 



Common in Lake Michigan, and in the small glacial lakes. Also cotnmon in the Illinois 

 river at Ottawa, Peoria, Havana and Meredosia, and in lakes about CJuincy. 



Percina caprodes (Rafint'sque). — Log Perch: Hog Perch: (iiant Darter. (.337) 



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

 eyes,' 'stone-totters,' 'horny-heads,' and other 'boys' tish ' " Its large size, cylindrical form. 

 yellowish color, with narrow black bars, and its pig-like snout will serve to distinguisli it 

 from other darters. 



Occurs infreciuenil>- in the south half of the State. Frequently taken northward in 

 gravelly situations. 



KEY TO ILLINOIS SPECIES OF THE GENUS HAHROPTERrS. 



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. PHOXOCEPH.\LUS. 



aa. Head more obtuse; lower jaw included, but mouth terminal: much dark coloration on 

 sides. 



b. (jill membranes either connected or not connected across the isthmus, the connec- 



tion, if present, not exceeding in width the diameter of the eye; border of pre- 

 tjpercle not serrate 



c. Dorsal spines 13 to l."> ^ H. .\sPRO. 



cc. Dorsal spines n or 12. 



d. Nape scaled ; no red or green markings; sides with 8 or 9 quadrate black spots. 



H. OLACHITAK. 



dd. Nape naked; coloration brilliant in life, variously yellowish, black, green, bronze, 

 and rust-red; 7 dark bars extending from lower part of side over back and down 

 opposite side H. evides 



bb. Cjill membranes broadly connected acrcKss isthmus; margin of preopercle serrate. 



H. SCIERIS. 



Hddroptcrus pliiuoccplnihis (Nel.son). (.'Ul) 



Form slender; head pointed; mouth iiearh' terminal: sides with quadr.ite or diamond- 

 shaped dark l)lotches. smaller ban in //. iis/'iv, sometimes i:rading into bands; back also 

 I lotched or banded with dark; spinous ilorsal with a band of orange-red. 



Taken from 77 localities, distributed throughout Illinois: usually found in the rapids of 

 large creeks or rivers; rare in southern Illinois. 



