422 



BULLETIN OF THE BUREAU OF FISHERIES 



have taken them spawning at the same season 5 to 8 miles west of Manistee in 40 to 

 80 fathoms on clay. There are, or were, probably other spawning grounds in the lake. 



Evermann and Smith (1896, p. 319) say that blackfins examined by them from off 

 Sheboygan, Wis., taken about November 12 and 18, were "ripe or nearly ripe with 

 some were partially spent." These fish may have had prema- 

 gonads, as appears to happen frequently in the Great Lakes 



spawn, * * * 

 turely developed 

 Leucichthys. 



Leucichthys nigripinnis nigripinnis of Lake Huron 



The Huron form resembles very closely the typical form, 

 may be compared at a glance: 



The chief characters 



H/S: 



Michigan, 3.5-3.9 (4.1). 

 Huron, (3.3) 3.4-3.8 (4.2). 

 Pv/P: 



Michigan, (1.5) 1.6-1.8 (2.2). 

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

 Av/V: 



Michigan, 1.2-1.5 (1.6). 

 Huron, (1) 1.1-1.4 (1.6). 



Gill rakers on the first branchial arch: 



Michigan, (41) 46-50 (52). 82 



Huron, (40) 46-50 (52) .83 

 Lateral-line scales: 



Michigan, (74) 80-87 (89). 



Huron, (72) 77-83 (88). 

 L/H: 



Michigan, (3.8) 4.1-4.4 (4.7). 

 Huron, (3.7) 4-4.2 (4.4). 

 H/E: 



Michigan, 4-4.4 (4.6). 

 Huron, (3.6) 3.9-4.2 (4.6). 



It appears from the foregoing that the Huron form has, on the average, a larger 

 head and eye and possibly fewer lateral-line scales and slightly longer paired fins. 



The color of living fish is like that of the typical specimens. Specimens in spirits 

 are also like those from Lake Michigan. The most noteworthy variation among 

 individuals of the same school (and this has been observed most frequently in Georgian 

 Bay) is the absence in some few examples of the characteristic bright blue body color 

 and the reduction of the usual pigmentation of the fins, especially of the ventral s. 

 These individuals differ from the rest in no other characters. 



Males, at least, are known to develop pearl organs during the breeding season, 

 but no examples in full breeding dress have been seen. 



VARIATIONS 



Racial variations. — The 71 specimens from Georgian Bay, compared in their 

 principal characters with the 63 specimens from Lake Huron, virtually all taken off 

 Alpena, Mich., do not show any differences to exist between the individuals of the 

 two groups, except that the former may have a somewhat smaller eye. 



Size variations. — All the collected specimens are over 200 millimeters in length, 

 and most of them are over 250 millimeters in length, so that it is not possible to sepa- 

 rate two groups of specimens for comparison according to size. 



No specimen of blackfin smaller than 208 millimeters has been seen by me, and 

 very few have been seen smaller than 230 millimeters. Specimens have not been 

 found to be sexually mature under 220 millimeters. 



,s All figures for Lake Michigan are based on an examination of 52 specimens, which range in length from 220 to 360 millimeters. 

 83 All figures for Lake Huron are based on an examination of 134 specimens ranging in length from 208 to 371 millimeters. 



