432 



BULLETIN OF THE BUREAU OF FISHERIES 



COMPARISONS al 



Nigripinnis regalis approaches most closely nipigon. The chief differences are 

 in the number of gill rakers on the first branchial arch, which in the former are not 

 known to number more than 54 and in the latter not less; in the body shape, which is 

 usually strongly ovate in side view in the former and elliptical in the latter; and in the 

 relative size of the eye as compared with the head. The value of H/E for nigripinnis 

 is (3.5) 3.7-4.1 (4.3) and for nipigon (3.8) 4.4-4.6 (5.2), with 71 per cent more than 

 4.3. The blackfin is pigmented much more heavily as a rule, especially on the abdom- 

 inal fins. 



A discussion of the difference between nigripinnis and zenithicus and reighardi 

 is given on pages 386 and 407. 



Only small nigripinnis regalis are comparable with hoyi, as hoyi does not attain 

 great size. The two species are always distinguishable by the more ovate body shape 

 of the former, by the much heavier pigmentation of body and fins and by the greater 

 number of gill rakers on the first branchial arch, which in nigripinnis number (44) 

 48-51 (54), with 68 per cent more than 48, and in hoyi (40) 42-46 (48). 



Nigripinnis regalis differs from artedi in body shape, which is ovate in side view 

 in the former and elliptical in the latter; in the longer paired fins and maxillary, and 

 the deeper body, as is indicated by the following figures: 



Pv/P: 



nigripinnis, (1.2) 1.4—1.6 (1.9), with 33 per cent more than 1.5. 

 artedi, (1.5) 1.6-1.8 (2), with 96 per cent more than 1.5. 

 Av/V: 



nigripinnis, (1.1) 1.2-1.5 (1.7), with 7 per cent more than 1.5. 

 artedi, (1.3) 1.5-1.6 (1.7), with 47 per cent more than 1.5. 

 H/M: 



nigripinnis, (2.4) 2.5-2.6 (3), with 14 per cent more than 2.6. 

 artedi, (2.5) 2.7-2.8 (3), with 87 per cent more than 2.6. 

 L/D: 



nigripinnis, (3.1) 3.5-4.0 (4.5), with 10 per cent more than 4. 

 artedi, (3.8) 4.1-4.6 (5), with 88 per cent more than 4. 



Artedi is also less pigmented, especially on the paired fins, which are never 

 conspicuously black as in nigripinnis. 



GEOGRAPHICAL DISTRIBUTION 



All the records of specimens taken by me and of those examined from the Uni- 

 versity of Toronto collection are given in Table 46 and are shown platted on the lake 

 chart in Plate 2. They show that the species has been taken in each of the three 

 lifts of the 2}^ a nd 2% inch nets made by me and that individuals also have been 

 obtained from numerous other localities, even in the commercial whitefish nets. 

 It is probable, then, that the species occurs throughout the lake where suitable 

 conditions obtain. 



BATHYMETRIC DISTRIBUTION 



My records show that the species was taken commonly on July 25, 1922, in 

 10 to 15 fathoms off the source of the Nipigon River, but more abundantly July 26, 



" The specimens compared in this section for proportions are those 200 millimeters or more in length, except artedi, which are 

 225 millimeters or more. Counts are given for specimens of all sizes. 



