524 



BULLETIN OF THE BUREAU OF FISHERIES 



The color in life and in spirits is not essentially different from that described for 

 the northern Lake Michigan specimens. The intensity of pigment varies with the 

 individual; possibly also with locality. All the specimens collected tend to be darker 

 than those that were obtained in the southern waters of Lake Michigan. Only an 

 occasional individual from Saginaw Bay has been found with the pigment inconspic- 

 uous on the abdominal fins, and such pale fish have been among the smallest in the 

 collection. 



Pearls are always present during the breeding season on all males and on the 

 majority of females. They occur conspicuously on the body, the head, and faintly 

 on all the fins. On the males they are developed best on the first row of scales above 

 and below the lateral line. They are slightly smaller on the next row dorsad and 

 ventrad and continue to diminish in size to the third or fourth rows above and the 

 fourth or fifth rows below the lateral line. On the surface of the body, dorsad to the 

 third or fourth rows above and ventrad to the fourth or fifth rows below, they are 

 faint and irregularly distributed, often two, three, or more on one scale. On the 

 first four rows above and below the lateral line there is usually only one large pearl 

 on each scale. This is rounded oblong in shape at its base, longer than wide, and is 

 situated in the center, occupying in its extreme development from one-fourth to one- 

 sixth of the exposed scale surface. The pearl is not of uniform thickness. Its two 

 lateral surfaces rise to meet in a line that is distinctly elevated above the remainder 

 of the button and runs lengthwise through its center. Often a much smaller and 

 similarly shaped pearl occurs on one or both sides of the larger one, slightly caudad to 

 its center. Along the cranial half of the lateral line there are often two pearls on each 

 scale, each about one-half the size of those in the first row above and below, or there 

 may be two or three small and unequal pearls. These decrease usually to one 

 small pearl on each scale on the caudal half of the line but remain virtually the same 

 size as on the cranial half. The pearls on the head are well developed and numerous 

 but small and irregularly distributed. They are most numerous on the dorsal 

 surface and on the lateral surface craniad of the operculum. On the suboperculum, 

 interoperculum, and operculum they are fewer, and on the branchiostegal membrane 

 a single row is present on each ray. The premaxillaries and the free edge of the 

 mandible alone are free from pearls. On the pectoral fins they are present in a row 

 running on both sides of the longest ray, being fainter on the inside surface. There 

 are other rows, chiefly on the distal halves of the other pectoral rays. On each 

 side of the longest ventral ray there is a row, and there are often broken rows on the 

 outside of some of the other rays. Besides these, there is a row on the first rays of 

 the dorsal, on the longest rays of the caudal, and on the scales of the adipose fin. 

 The occurrence of pearls in females is approximately the same as in the males, 

 though the maximum development attained is greater in the latter. 



VARIATIONS 



Racial variations. — There is reason to believe that the whitefish are local in their 

 habits, and therefore races with more or less definite characteristics might be looked 

 for. The existence of no races with distinctive taxonomic characters is disclosed by 

 my analysis of the specimens in my collection, but the material is not sufficiently 

 complete to warrant a positive statement. In certain localities the fish have seemed, 



