CRISTIVOMER — GREAT LAKE TROUT 55 



much more distinctive name of cisco, already frequently used for it 

 but now commonly limited to a variety of the species found in the 

 smaller lakes of Wisconsin and of Indiana, but not in those of Illi- 

 nois. 



In food and habits it is similar to the common whitefish, al- 

 though it is notorious for its enormous destruction of the spawn of 

 the latter, upon whose multiplication, in view of its own greater abun- 

 1; i nee arid the rapidly decreasing supply of whitefish, it must place a 

 serious check. Like the whitefish it spends the summer and the 

 winter in the deeper water of its habitat, moving shorewards in 

 spring evidently in search of food, and again in fall for the deposit 

 of its spawn, which takes place chiefly in November. Its eggs arc 

 laid in shallow water, preferably upon a sandy bottom, although 

 it sometimes spawns on the mud along the borders of the shallower 

 waters of the lakes and in the mouths of their tributary streams. 



It is caught with gill-nets in shallow water from April to 

 the last of May, but the larger part of the catch is obtained by 

 pound-nets. Up to 1899 it seems to have withstood successfully 

 the enormous drain of our fisheries, the yield of that year being more 

 than double that of 1885, while the catch of whitefish, on the other 

 hand, had diminished to less than a third. 



In addition to the commi in lake herring, four other species of the 

 genus Argyrosonnis (A. hoyi, the mooneye cisco; A. prognathus, the 

 longjaw; A. nigripennis, the bluefin; and .4. tullihec, the tullibee) 

 are more or less commonly taken in Lake Michigan. None of these 

 species is as abundant as the lake herring (,4. artedi), however, and 

 none, unless the bluefin, is taken at all frequently in southern Lake 

 Michigan, within the limits of this state. For purposes of the 

 present report all of these species are sufficiently characterized in the 

 key to the species of Argyrosomus preceding. 



Genus CRISTIVOMER Gill & Jordan 



(great lake trout) 



Body moderately elongate; mouth large; hyoid with a band of 

 strong teeth; vomer boat-shaped, with a raised crest behind the head 

 and free from its shaft, this crest being armed with teeth; caudal little 

 forked; scales very small. 



