GREAT LAKES COREGONIDS 



461 



H/E: 



hoyi, (3.3) 3.6-3.8 (4.2), with 16 per cent more than 3.8. 

 artedi, (3.6) 3.8-4 (4.4), with 66 per cent more than 3.8. 

 H/M: 



hoyi, (2.3) 2.4-2.6 (2.7), with 7 per cent more than 2.6. 

 artedi, (2.5) 2.7-2.9 (3.2), with 89 per cent more than 2.6. 

 Pv/P: 



hoyi, (1.4) 1.7-1.9 (2.2), with 21 per cent more than 1.9. 

 artedi, (1.7) 1.9-2.1 (2.3), with 68 per cent more than 1.9. 

 Av/V: 



hoyi, (1) 1.2-1.4 (1.7), with 1 per cent more than 1.5. 

 artedi, (1.3) 1.6-1.7 (1.9), with 84 per cent more than 1.5. 



On the average the mandible in hoyi probably is longer than the upper jaw more 

 often than in artedi, and certainly it is seldom shorter, while in artedi it is frequently 

 shorter. The state of development of sex organs frequently is a valuable criterion, 

 also. Specimens of hoyi are found to mature sexually as small as 110 millimeters, while 

 artedi usually do not mature under 160 millimeters. Hoyi spawns in February or 

 March and artedi in November, so that the state of maturity of the sex organs also 

 may be a character. Hoyi, as a rule, is much less pigmented, especially on the dorsal 

 surface. 



The distinguishing characters between hoyi and johannse, alpense, zenithicus, 

 and nigripinnis are, in the main, the same as described for these forms for Lake 

 Michigan on pages 352, 366, 390, and 419, except that in the case of Huron the differ- 

 ence in size attained by hoyi and these four species is still more marked. Necessary 

 modifications of the comparisons cited are given below : 



■Gill rakers on the first branchial arch: 



hoyi, (37) 40-43 (47), with 3 per cent more than 44. 

 johannse, (25) 27-31 (35) . 23 



alpense, (31) 33-37 (41), 24 with 24 per cent more than 36. 



zenithicus, (32) 35-37 (41) , 25 with 47 per cent more than 36. 



nigripinnis, (40) 46-50 (52), 26 with 83 per cent more than 44. 

 Lateral-line scales: 



hoyi, (63) 68-76 (84), with 12 per cent more than 76. 



johannse, (67) 77-86 (91), with 92 per cent more than 76. 



alpense, (70) 76-83 (91), 24 with 74 per cent more than 76. 



zenithicus, (70) 72-81 (88) , 25 with 56 per cent more than 76. 



nigripinnis, (72) 77-83 (88), with 81 per cent more than 76. 

 Pv/P: 



hoyi, (1.4) 1.7-1.9 (2.2), with 21 per cent more than 1.9. 

 johannse, (1.2) 1.5-1.7 (2), with 3 per cent more than 1.9. 

 alpense, (1.6) 1.8-2 (2.4), with 41 per cent more than 1.9. 

 zenithicus, (1.7) 2-2.2 (2.6), with 73 per cent more than 1.9. 

 nigripinnis, (1.2) 1.4-1.7 (1.9). 



23 Figures lor johannse, for gill rakers, are given for 441 specimens; for scales for 258 specimens. All others are based on an exami- 

 nation of 92 specimens ranging in length from 132 to 199 millimeters. 



" Figures for alpense, except those for scales, are based on an examination of 204 specimens between the lengths of 131 and 209 

 millimeters. Figures for scales are given for 323 specimens of all sizes. 



! » Figures for zenithicus, except those for scales, are based on an examination of 77 specimens ranging in length from 139 to 199 

 millimeters. Those for scales are given for 144 specimens of all sizes. 



!8 Figures given for nigripinnis are based on an examination of 134 specimens ranging in length from 208 to 371 millimeters. 



