48 FISHES OF ILLINOIS 



Species numerous (about 150 known), abundant and widely 

 distributed in all seas, usually swimming in immense schools. 

 Many species ascend 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 CLUPEID^ 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 

 cheeks 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 tenninal, 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, mostl}^ 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) 



Rafinesque, 1820, Ichth. Oh., 39. 



J. & G., 266 (Clupea); M. V., 73 (Clupea) ; J. & E., 1,425; N..44 (misspelled); J., 

 55; F., 73 (Clupea); F. F., II. 7, 439; L., 20. 



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 

 ^; '.i olive-gray with strong bluish luster; sides 



^ ' light olive-green, shading to silvery white, 

 ■ " with golden luster; belly opaque milk- 



Fn,. ij white; no dark spot behind opercle. 



Head pointed, 3.7 to 4 in length; width 

 head 2.3 to 2.6 in its length; interorbital space 5.8 to 6.3 in head, less 

 than eye; eve 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 



