GREAT LAKES COREGONIDS 



491 



chief characters below. The Michigan specimens are given as typical of artedi 

 because there are only a few available examples of that form from Erie, ancTit has 

 been shown that the forms from the two lakes are probably identical. 



H/S: 



Erie, albus, (3.6) 

 Michigan, artedi, 

 Huron, artedi, (3, 



Pv/P: 



Erie, albus, (1.6) 

 Michigan, artedi, 

 Huron, artedi, (1. 



Av/V: 



Erie, albus, (1.4) 

 Michigan, artedi, 

 Huron, artedi, (1. 



L/D: 



Erie, albus, (2.8) 

 Michigan, artedi, 

 Huron, artedi, (3. 



3.8^ (4.5). 



(3.3) 3.7-4 (4.4). 

 5) 3.7-4 (4.3). 



1.9-2.1 (2.5). 

 (1.6) 1.9-2.2 (2.6). 

 7) 2-2.2 (2.6). 



1.5-1.8 (2.1). 



(1.4) 1.6-1.8 (2.3). 



4) 1.6-1.8 (2.1). 



3.3-3.7 (4.8). 

 (3.6) 4-4.9 (5.3). 



5) 4-4.7 (5.4). 



Gill rakers on the first branchial arch: 



Erie, albus, (41) 44-48 (53) . 50 



Michigan, artedi, (41) 46-50 (55). 61 



Huron, artedi, (40) 45-50 (53). 52 

 Lateral-line scales: 



Erie, albus, (64) 70-81 (89). 



Michigan, artedi, (68) 77-87 (94). 



Huron, artedi, (68) 76-86 (98) , 52 

 L/H: 



Erie, albus, (4.1) 4.4-4.7 (5.2). 

 Michigan, artedi, (4.1) 4.3-4.5 (5.) 

 Huron, artedi, (4) 4.3-4.6 (5). 63 

 H/E: 



Erie, albus, (3.8) 4.2-4.5 (4.9). 

 Michigan, artedi, (3.6) 4-4.2 (4.7). 

 Huron, artedi, (3.7) 3.9-4.3 (5.1). 

 H/M: 



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

 Michigan, artedi, (2.5) 2.7-3 (3.3). 

 Huron, artedi, (2.6) 2.8-3 (3.3). 



These figures show that the Huron form is very like the albus form of Erie, 

 except in body depth. The figures indicate that the former has possibly a few more 

 gill rakers on the average, more scales in the lateral line, a larger eye, and much 

 less body depth. The Huron fish seem to be very like the artedi of Lake Michigan 

 and therefore may be given the same name. The inclusion of the extremely developed 

 North Channel manitoulinus with the Huron specimens would lower the minimum 

 value given in parentheses to the left in the case of L/H, H/E, H/M, Pv/P, Av/V, 

 and L/D. As in every instance cited a proportion is involved, it follows that the 

 North Channel individuals have a longer head, eye, maxillary, paired fins, and greater 

 body depth. 



The mandible has been found to be longer than the upper jaw in only 11 per 

 cent of the Huron specimens and usually is equal or shorter, as in Lake Erie. 



The color in life of most Huron specimens is very like that of the blueback of 

 Erie, namely, deep blue green on the back, though often specimens are seen that 

 are as pale as the common Erie type. The difference in coloration is particularly 

 conspicuous when a school is seen swimming near the surface of the lake. A few 

 will be lighter in color on the back than the rest. This, by the way, is no less true 

 in any of the lakes. All Huron specimens, however, tend to show more pigmenta- 

 tion, particularly on the back and head. The ventrals, while often immaculate, 



80 Figures of Lake Erie albus for proportions are based on an examination of 148 specimens ranging in length from 225 to 402 

 millimeters, those for gill rakers on 298, and for lateral-line scales on 735. 



11 Figures for Lake Michigan artedi are given for 148 specimens ranging in length from 225 to 367 millimeters, except those for 

 gill rakers and lateral-line scales, which are based on 391 fish. 



t! Figures for Lake Huron so designated are based on an examination of 343 specimens ranging in length from 125 to 371 milli- 

 meters. Those figures that deal with proportions are based on an examination of 215 specimens ranging in length from 225 to 371 

 millimeters. 



13 From proportional figures for Huron the 20 specimens of manitoulinus have been deducted. 



