48 FISHES OF ILLIXOIS 



Species numerous (about 150 known), abundant and widely 

 disl filiated in all seas, usually swimming in immense schools. 

 Many species ascen 1 fresh waters in spring to spawn and a few 

 are permanent residents in fresh water. Two genera are found in 

 streams tributary to the Atlantic and the Gulf and in the Mississippi 

 Valley. 



Key to the Genera of CLUPEIDjE found in Illinois 



a. Premaxillaries meeting at a large angle, so that the tip of the upper jaw does 



not appear to be notched, cheeks longer than deep; teeth feeble... Pomolobus. 



aa. Premaxillaries meeting in front at a very acute angle, so that the emarginate 



front of the upper jaw receives the slender tip of the lower; fore part of 



clucks very deep, deeper than long; jaws toothless Alosa 



Genus POMOLOBUS Rafinesque 



(alewives) 



Body rather elongate, more or less compressed; belly sharp-edged, 

 strongly serrated before and behind ventrals; mouth terminal, oblique; 

 jaws about equal, the upper somewhat notched at tip; mandible shutting 

 within maxillaries; teeth feeble, variously placed; dorsal short, nearly 

 median, its posterior ray not prolonged in a filament; scales thin, cycloid. 

 Species numerous, mostly anadromous, inhabiting both northern and 

 tropical seas ; one species found in fresh waters of the Mississippi Valley. 



POMOLOBUS CHRYSOCHLORIS Rafinesque 

 (golden shad; skipjack; blue herring) 



E., 1,425; N.. 44 (misspelled); | , 



Length 15 inches; body elongate, com-' 



pressed, greatest width somewhat less 



than 2\ in depth in adults; depth 3.6 to 



4.3; depth caudal peduncle 1.4 to 1.6 in 



its length. Color silvery to greenish with 



bluish and golden reflections ; back light 



M olive gray with strong bluish luster; sides 



light olive-green, shading to silvery white, 



with golden luster; belly opaque milk- 



p IG [3 white; no dark spot behind opercle, 



Head pointed. 3.7 to 4 in length; width 



head 2.3 to 2.6 in il length; interorbital space S.8 to 6.3 in head, less 



4.5 to 5.9 in head; adipose eyelid present; nose 4.3 to 5.2 



in head; mouth large, terminal, opening very high, lower jaw strongly 



