GREAT LAKES COREGONIDS 



457 



The time of spawning, then, appears to be during March. It may begin in certain 

 areas or at certain seasons even as early as late February. The species has been 

 found spawning at a depth of 28 fathoms, but it may spawn in shallower or deeper 

 water. The character of the bottom selected is not known. Breeding grounds are 

 known to exist off Grand Haven, Mich.; Michigan City, Ind.; and Milwaukee 

 and Port Washington, Wis.; but considering the wide distribution and abundance 

 of the species, there are no doubt others to be found off most of the other ports on 

 the lake. 



Leucichthys hoyi of Lake Huron 



The Lake Huron form is like the Michigan form in respect to body shape and 

 other systematic characters, but it seldom grows so large. The largest specimen 

 obtained in the lake measures only 221 millimeters, as compared with 265 milli- 

 meters for Lake Michigan, and only nine individuals have been seen over 200 milli- 

 meters in length, whereas in Lake Michigan such fish are taken often in commercial 

 quantities. The principal systematic characters capable of numerical expression 

 are compared for the two forms below : 



Gill rakers on the first branchial arch: 



Michigan, (37) 41-44 (48). 18 



Huron, (37) 40-43 (47). 10 

 Lateral-line scales: 



Michigan, (60) 67-77 (84). ' 8 



Huron, (63) 68-76 (84). 

 L/H: 



Michigan, (3.6) 4-4.2 (4.5). 

 Huron, (3.5) 3.8-4.1 (4.5). 

 H/E: 



Michigan, (3.3) 3.7-4 (4.2). 

 Huron, (3.3) 3.6-3.8 (4.2). 



It appears from these figures that the two forms are quite similar and that they 

 differ only in that the head and eye average proportionally somewhat larger in the 

 Huron form, but these differences may well be due to inequality in size of the indi- 

 viduals of the groups compared. 



The color in life is hot conspicuously different from that of the Lake Michigan 

 specimens. Preserved fish are also little different. 



Pearl organs are developed by males in the breeding season, as evidenced by 

 breeding fish taken at Harbor Beach, Mich., on March 15, 1919. Females probably 

 also have pearls, but those in the collection had none, possibly having lost them by 

 friction in transit, as did many of the males. The development is not different 

 from that described for the Lake Michigan specimens, except that there are, on the- 

 average, fewer dorsolateral and ventrolateral scale rows, on the scales of which two- 

 or more pearls appear regularly. The pearls of the back and belly are also less scat- 

 tered and more often are grouped around the free edge of the scale. It is possible,. 



H/M: 



Michigan, (2.3) 2.5-2.6 (2.8) 

 Huron, (2.3) 2.4-2.6 (2.7). 

 Pv/P: 



Michigan, (1.3) 1.7-2 (2.5). 

 Huron, (1.4) 1.7-1.9 (2.2). 

 Av/V: 



Michigan, (1) 1.2-1.4 (1.6). 

 Huron, (1) 1.2-1.4 (1.7). 



'8 These figures for Lake Michigan are based on an examination of 1,161 specimens from 82 to 265 millimeters in length. The 

 other unmarked figures are given for 1,024 individuals between the length limits of 82 and 199 millimeters, inclusive. 



" These figures for Lake Huron, excepting those for H/M, which are given for 58 specimens, are based on an examination of 

 807 specimens between the lengths of 79 and 221 millimeters, inclusive. There are only 4 specimens less than 100 millimeters in 

 length and only 9 over 200 millimeters, and their exclusion from the tables does not affect the range of the figures given. 



!0 One hundred and eight specimens, - — - _ 



