GREAT LAKES COREGONIDS 



499 



The food of the herring varies, no doubt, with the season. When the schools are 

 inshore they probably feed heavily on the larval insects that are present in the shallow 

 water and on such other items of food as come in their way. At such times they 

 are known to take the hook. Small spoons, pearl buttons, or minnows are the 

 commonest baits used. At other times their food is probably largely plankton 

 organisms, as they are not known to migrate in Lake Huron to the depths inhabited 

 by Mysis, the chief food element of the deep-water Leucichthys, and no insect larvae 

 occur except along the shores. 



Leucichthys artedi artedi and artedi albus of Lake Superior 



The herring population of Lake Superior is constituted of the two types that 

 are found in Lake Erie, except that the elongated terete form, which is rare in Erie, 

 is the most abundant, and the deeper-bodied form, which is the predominating form 

 of Erie, probably is confined to the warm bays on the north shore. In general, the 

 systematic characters of the forms that occur in the two lakes are not very different. 

 All collected specimens of both races are grouped together for each lake in the com- 

 parisons of the various systematic characters given below. There are available so 

 few specimens of the rare types in both lakes that it does not seem worth while to 

 separate them for comparison more than has been done in Tables 67 and 74, where 

 20 large albus and 10 large artedi for Lake Erie and 4 large albus and 6 large artedi 

 for Superior are analyzed in detail. 



Gill rakers on the first branchial arch : 



Erie, (41) 44-48 (53) . 55 



Superior, 38 (41) 45-48 (53) .*> 

 Laterial-line scales: 



Erie, (64) 71-81 (89). 



Superior, (72) 84-93 (105). 59 

 "L/H: 



Erie, (4.1) 4.3-4.7 (5.2). 

 Superior, (4.1) 4.3-4.6 (5.1). 

 H/M: 



Erie, (2.5) 2.7-2.9 (3.3). 

 Superior, (2.5) 2.7-3 (3.1). 



H/S: 



Erie, (3.6) 3.8-4 (4.5). 

 Superior, (3.4) 3.6-3.9 (4.3). 

 Pv/P: 



Erie, (1.6) 1.9-2.1 (2.5). 

 Superior, (1.7) 2-2.2 (2.8). 

 Av/V: 



Erie, (1.4) 1.6-1.8 (2.1). 

 Superior, (1.3) 1.6-1.8 (2.3). 

 L/D: 



Erie, (2.8) 3.3-3.7 (4.8). 

 Superior, (3.7) 4.3-5 (5.9). 



The data indicate that the Superior artedi has much less body depth and more 

 lateral-line scales than the albus of Erie. The pectorals also are somewhat shorter 

 and the snout usually a trifle longer. The counts indicate that the fin rays are, on 

 the average, more numerous in the Superior fish, but these characters have not been 

 investigated more closely than has been shown in Tables 67 and 74. The scale rows, 

 of course, are also more numerous in the artedi form, wherever it may occur. 



Comparing the two types of the two lakes with one another, it appears that the 

 Superior artedi race probably has more lateral-line scales than individuals of that 

 type in Lake Erie. Individuals of the albus of Superior can be matched exactly 



m These figures for Lake Erie are given for 313 specimens ranging in length from 128 to 402 millimeters. Those for scales are 

 based on 750 specimens of the same size range, but all figures for proportions are based on only 163 of the specimens 225 millimeters 

 or more in length. 



8 » These figures for Lake Superior are based on an examination of 257 specimens, which range in length from 135 to 435 milli- 

 meters. All figures dealing with proportions are given only for the specimens of this group 225 millimeters long or longer, which 

 are 185 in number. 



