554 



BULLETIN OF THE BUREAU OF FISHERIES 



indicating but little change in the proportion between head length and total length 

 after maturity. The eye decreases more conspicuously in size with age. In speci- 

 mens 200 millimeters or less in length the H/E ratio ranges from 3.2 to 4.1; in those 

 less than 300 millimeters, (4) 4.1-4.5 (4.6); in those 300 millimeters or over, (4.3) 

 4.5-5.1. The differences in the Av/V ratio are distinctive only for the group of 

 individuals less than 200 millimeters and for that of the largest fish. The values are 

 (1.7) 1.8-2.1 (2.2) and (1.9) 2-2.2 (2.5), respectively. 



The coloration of small specimens is distinctly different from that of adults. 

 The fingerlings (65 to 77 millimeters long) taken at the mouth of the Devils Track 

 River near the international boundary on July 17, 1922, have the back pale sepia 

 with two rows of irregular black spots 1 to 2 millimeters in diameter lying at intervals 

 of less than a diameter close to the median line. Often two spots join and make an 

 elongated patch. The sides are silvery, with a row of black dots much smaller than 

 those on the back lying halfway between the lateral line and the dorsal. These spots 

 also are irregular in size, shape, and spacing. Those in the area anterior to the caudal 

 edge of the dorsal are largest (about 1 millimeter in diameter) and are arranged in a 

 more or less straight line. In the region caudad to this point the spots become smaller 

 and are scattered. At each end of the lateral line lies a conspicuous blackish patch 

 2 to 3 millimeters in diameter. On the line, spaced at intervals of 2 to 5 millimeters, 

 are found 7 to 10 other patches of similar size and shape. The belly is white. The 

 iris is silvery, tinged with sepia. The paired fins are yellowish, with the yellow of the 

 anal fainter. The ring of pigment around the free edge of the scales of the back 

 characteristic of the adults is very evident. 



The spots seem to disappear first on the back. The pigment apparently diffuses 

 over the surface. The dots on the side above the lateral line linger longest and usually 

 split so as to give the appearance of two or three irregular rows. They increase in 

 size as the fish grows but become proportionally smaller until they finally fade. In 

 the specimens 134 to 200 millimeters in length the dorsal spots are paling. In a 

 few mature fish 260 millimeters long there still remain traces of the lateral spotting. 



No individuals ranging in size between 200 and 245 millimeters were seen, and 

 these limits are those between the immature and mature fish. The maximum size 

 reported for the lake is about 5 pounds. 



GEOGRAPHICAL DISTRIBUTION 



I have collected specimens of pilot from Rossport, Black Bay, and Batchawanna 

 on the Canadian shore, from Stannard Rock reef, the Apostle Islands, and from Grand 

 Marais, Minn. Data for these are given in Table 100. They are also shown platted 

 on the chart of the lake in Figure 3. Pilot are known, from the reports of the fisher- 

 men, out of Sault Sainte Marie (Will Muntinga), Grand Marais, Mich. (Charles 

 McDonald), Marquette, Mich. (Will Parker), Ontonagon, Mich. (Earl Couture), 

 Gargantua, Ontario (J. A. McMillan), and Michipicoten Island (L. McArthur), and 

 it is probable that the species is distributed generally along the shores of the lake 

 where bottom conditions are suitable. 



