GREAT LAKES COREGONIDS 379 



green between the nares. The paired fins and often the bases of the others are 

 faintly flesh colored. The dorsal margin and often the distal half of the rays of 

 the pectoral, the cranial margin and a wide distal band of the dorsal and the lateral 

 borders, the distal third of the longest and half of the shortest rays of the caudal 

 are smoky to black in hue. Black may often be present more or less conspicuously 

 on the ventrals and the anal, also. 



All color fades after death, and after prolonged preservation the silvery tone 

 usually disappears, leaving characters of pigmentation more conspicuous. The 

 pigment, which in life is evident on the entire dorsal surface, is revealed in dimin- 

 ished abundance on the sides above the lateral line. Below the lateral line and on 

 the cheeks pigment is scattered. 



Males, at least, acquire pearl organs during the breeding season, as is indicated 

 by the fact that a few individuals taken several weeks previous to the spawning 

 season have traces of these excrescences. Their full development probably is not 

 different from the development exhibited by the breeding male of Lakes Huron and 

 Michigan. 



VARIATIONS 



Racial variations. — Specimens have been collected from 12 localities distributed 

 rather uniformly along the shore of the lake. The number of specimens preserved 

 from each port varies, for the most part, between 50 and 200, and the various collec- 

 tions are fairly homogeneous in respect to size. A comparison of the various locality 

 groups shows no differences in any of the characters examined. There are indica- 

 tions that specimens under 200 millimeters vary according to locality and habitat. 

 Tor example, those small fish that have been taken from depths of more than 60 

 fathoms appear to have, on the average, a slightly shorter snout and greater body 

 •depth (even making allowance for the bloating attendant on bringing the fish to 

 the surface) than those from shallower water. 



Size variations. — Rather marked variations are exhibited by the small specimens. 

 In Table 25 are compared extensively 10 specimens of less than 200 millimeters in 

 length and 10 specimens of more than 200 millimeters in length. In addition, there 

 are given in Tables 8 to 11 a comparison of certain characters of all the specimens 

 collected, which in these tables have been separated similarly according to size. 

 The most noteworthy data are summarized below: 



Gill rakers on the first branchial arch : 



Small fish, (32) 36-41 (45), with the mode at 38. 



Large fish, (34) 39-43 (46), with the mode at 40. 

 L/H: 



Small fish, (3.5) 3.7-4 (4.2), with the mode at 3.9. 

 Large fish, (3.6) 3.8-4.1 (4.4), with the mode at 4. 

 H/E: 



Small fish, (3.6) 3.7-4.1 (4.5), with the mode at 3.9. 

 Large fish, (3.9) 4.2-4.6 (5.1), with the mode at 4.4. 

 H/M: 



Small fish, (2.3) 2.4-2.6 (2.7), with the mode at 2.5. 

 Large fish, (2.1) 2.3-2.5 (2.7), with the mode at 2.5. 



H/S: 



Small fish, (3.1) 3.3-3.7 (3.9), with the mode at 3.5. 

 Large fish, (3.1) 3.3-3.6 (4), with the mode at 3.4. 



