104 NORTHERN FISHES 



1936) . This genus is characterized by a single flap between the openings 

 of each nostril, which differentiates it from the genus Coregoniis. The 

 absence of teeth also distinguishes it from the other coregonids. 



COMMON MENOMINEE WHITEFISH (Pilot Fish, 

 Round Whitefish) 



Prosopium cylindraceum quadrilaterale (Richardson) 



The Menominee whitefish is a more or less ovate fish with silvery 

 sides and a dark-bronze back. The back is usually more deeply colored 

 than those of the common whitefishes. The upper jaw contains a large 

 premaxillary, which is greater in width than in length. The mandible is 

 contained not less than 2.7 times in the head. The premaxillary is usually 

 contained more than 3.8 times in the head. No vestigial teeth are 

 present. The gill-rakers number 15-20. During the spawning season 

 pearl organs are found on the sides of the bodies of both males and 

 females, but not on the heads. They reach a weight of 3 to 4 pounds. 



Menominee whitefish are found throughout northern North America 

 from the Arctic Ocean to the Great Lakes and New England. They 

 occur in all the Great Lakes but Erie and the tributary Nipigon. In 

 Minnesota they occur occasionally in Lake Superior, where they move 

 in schools along the shores. Apparently they do not go out into deep 

 water. They were formerly abundant but are now caught only occa- 

 sionally. Koelz reports that they spawn in late November or December 

 at the mouths of the Devil Track and Cascade rivers. From Decem- 

 ber 14-23, 1923 they spawned in considerable numbers in shallow 

 water off the mouth of the French River. The eggs were large for a 

 whitefish, running 21,303 to the quart and having a diameter of 0.147 

 of an inch. Although an excellent food fish, this species is not abundant 

 enough at present to be of great commercial value. 



