April, iqio. Fishes of Chicago — Meek and Hildebrand. 291 



Coregonus quadrilateralis Richardson. Menominee Whitefish. 



Heads; depth 4.7; D. 11; A. 10; scales 80 to 90. 



Body elongate, not much compressed, the dorsal region little 

 elevated; head long, the snout compressed and bluntly pointed; in- 

 terorbital space 3.5 in head; diameter of eye 4.7 to 5.5; snout 3.8; 

 mouth narrow, small, the maxillary not reaching eye; gill rakers 

 short and stoutish, 7+10 in number, lower jaw the shorter; lateral 

 line complete. 



Color dark bluish above, silvery below. 



Length 15 inches. 



Lakes of New England, Great Lakes to the Yukon. 



Lake Michigan, Chicago. 



Genus Arg'yrosomus Agassiz. 



Ciscoes; Lake Herrings. 



Body elongate, little compressed; head larger, the snout pointed, 



the premaxillary with its cutting edge nearly horizontal; lower jaw 



the longer; jaws toothless or nearly so; gill rakers long and slender; 



about 40 on the lower limb; caudal fin deeply forked. 



a. Lower fins pale, or sHghtly tipped with darker. 



b. Eye large, its diameter not much if any less than the length 

 of the snout, 3.5 to 4.5 in head. 



c. Maxillary 3.3 to 3.6 in head; lower jaw projecting beyond the 

 upper; gill rakers long and numerous, about 47 "on first arch. 



huronius, 291 



cc. Maxillary 2.6 to 3.0 in head, lower jaw scarcely projecting; gill 



rakers 39 to 40 on first gill arch. hoyi, 292 



bb. Eye. small, its diameter less than length of snout, about 5 in 



head; mandible half as long as head. prognatkiis, 292 



aa. Lower fins blue black; gill rakers at least 50 on the first arch. 



nigripinnis, 293 



Argyrosomus huronius Jordan & Evermann. Lake Herring; 

 Cisco and Blueback Herring of Lake Michigan. 



Head 4.1 to 4.5; depth 4.5 to 5.2; D. 10; A. 12; scales 75 to 90. 



Body elongate, not much compressed; head rather long pointed; 

 mouth large, the maxillary reaching nearly to middle of the pupil; 3.2 

 to 3.5 in head; lower jaw the longer; mandible 2.1 in head; inter- 

 orbital space T).T) in head; diameter of eye 4.0 to 4.5 ; snout 3.5 to 4.0; 

 gill rakers long and slender, 15 to 17+28 to 34 on first arch; lateral 

 line complete. 



