506 



BULLETIN OF THE BUREAU OF FISHERIES 



The color in life was not recorded. Fish observed swimming around the dock at 

 Macdiarmid showed the characteristic blue green color on the back, and it is likely 

 that the two forms are not very different in coloration. Preserved specimens from 

 which all color has faded are only a trifle darker on the dorsal surface, and the fins 

 also somewhat more pigmented. The anal and the ventrals frequently show more 

 or less pigment. 



No specimens were seen during the breeding season, and it is not known that 

 pearl organs are developed. It is probable, however, that they are, and their develop- 

 ment is not likely to differ from that exhibited by the species in the other lakes. 



VARIATIONS 



Racial variations. — So few specimens have been collected from any part of the 

 lake that nothing can be said about the development of local races. No tendencies 

 to vary in a definite direction are indicated by any of the specimens that I have seen. 



Size variations. — Only 13 individuals 225 millimeters or more in length have been 

 collected, and none of these are more than 253 millimeters long, so that it is not 

 possible to form two contrasting size groups. The meager data given in Tables 8 

 to 11, where the specimens of 225 millimeters or more in length are compared in 

 several characters with the group of smaller individuals, and Table 76, in which two 

 specimens of less than 200 millimeters are compared extensively with eight of more 

 than that limit, do not indicate any changes with growth, unless it be that the eye 

 becomes relatively smaller. Specimens usually are sexually mature at 165 millimeters 

 and occasionally even at 140. 



COMPARISONS 



In external characters artedi is very like nipigon. Apparently it does not grow 

 so large as this form, which often is found over 300 millimeters in length, as compared 

 with the largest collected artedi at 253 millimeters. The most trenchant difference 

 between the two species, however, is the number of gill rakers on the first branchial 

 arch, which in artedi are not known to number more than 53, while in nipigon no speci- 

 mens are known with less than 54. The eye in artedi appears also to average dis- 

 tinctly larger. There are no specimens with a higher value for H/E than 4.1, and 

 only two specimens of nipigon with a lower value than 4.1. The artedi, however, are 

 on the average much smaller than the nipigon, and in specimens of comparable size 

 the differences probably would not be so well marked. The maxillary, snout, and 

 paired fins also average shorter in artedi, and the body has much less depth. No 

 collected specimens of artedi have a value for L/D less than 3.8, while 66 per cent of 

 the tullibees have a value less than 3.8. These characters may be compared better 

 by consulting Tables 76 and 80, in which 10 specimens of each species are analyzed in 

 detail. The fins of artedi, especially the paired fins and the anal, show less pigment 

 than in nipigon, in which form almost all are invariably and often considerably pig- 

 mented. Another valuable criterion for separating the species is the state of the 

 sex organs. No specimen of nipigon has been found to be sexually mature under 250 

 millimeters in length, while artedi usually is mature at 165 millimeters or less. 



A discussion of the differences between artedi and the other species of Leucichthys 

 in the lake is given under the heading "Comparisons" in the accounts of these species. 



