GREAT LAKES COREGONIDS 



401 



[15-1 7]. 56 The paired fins are short. The pectoral length divided into the distance 

 from its insertion to that of the ventral equals 2.1 [(1.7) 2.0-2.5 (2.8)]. The length of 

 the ventral is contained 1.4 [(1.2) 1.4-1.7 (1.9)] times in the distance from its origin to 

 the anal. 



The color of living specimens differs in only minor details from that of other 

 chubs. After preservation, as in ad species, pigmentation becomes more conspicuous. 

 The entire dorsal surface is pigmented more or less heavily and evenly. The pigment 

 becomes denser in the prenarial area and usually shows very dark on the premaxillaries 

 and on the tip of the mandible. It continues often in a black rim along the cutting 

 edge of the maxillaries. The preorbital area, the postoculars, and at least half of the 

 maxillary are pigmented abundantly. On the cheeks and on the sides of the body 

 pigment diminishes rather gradually as the ventral surface is approached. It is absent 

 on the belly. Often the dorsal border of the pectoral and sometimes the inner surface 

 of its longest rays are lined with pigment. The cranial margin and a wide distal band 

 of the dorsal and the lateral borders, the distal third of the longest and half of theshort- 

 est rays of the caudal are smoky to black in hue. A few dots of pigment are often evi- 

 dent on the membrane of the anal. The ventrals are usually immaculate but may show 

 more or less pigment, especially in the north. 



Males and at least some females acquire pearl organs during the breeding season. 

 There are no specimens available from which to prepare a description of the pearls 

 at the height of their development, but onemale taken on August 18, 1920, off Wash- 

 ington Harbor, Wis., exhibits nuptial adornment about like that described for johan- 

 nse on page 350. 



VARIATIONS 



Racial variations. — Specimens taken in the northern waters are, on the average, 

 different from those of the southern half of the lake. Northern fish tend to have a 

 longer snout and maxillary and, as has been stated previously, average more pig- 

 mented on the fins. Some specimens have these parts developed to so great a degree 

 that they resemble closely specimens of zenithicus. The values of these two char- 

 acters in northern and southern specimens 200 millimeters or more in length are given 

 below. The specimens have been divided according as their origin is north or south 

 of a line drawn south of Washington Island, Wis., and Frankfort, Mich. 



H/S: 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 4.2 4.3 4.4 



Northern fish 1 3 28 27 41 30 17 13 4 2 0 1 ._ 



Southern fish 4 18 35 22 22 22 8 1 0 1 



H/M: 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 



Northern fish 1 8 35 46 44 24 4 2 



Southern fish ._ __ 3 38 50 37 7 



MS/E: 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 



Northern fish 2 5 12 20 46 39 17 12 4 1 



Southern fish 2 15 41 36 32 5 2 __ __ _. 



Size variations. — In Table 33, 20 specimens are compared extensively, half of 

 them less than 200 millimeters in length and half of them more than 200 millimeters. 

 In Tables 8 to 11 values for several characters are given for all the specimens of the 



IS Forty-four specimens. 



