514 



BULLETIN OF THE BUREAU OF FISHERIES 



12 [11-12 (13)] 64 anal rays, 12 [12 (13)] 64 ventral rays, 15 [(15) 16-17 (18)] 64 pectoral 

 rays, and 8 [8-9 (10)] 64 branchiostegal rays. 



The appearance of the species in life is silvery, with the underlying tints of green 

 and the superficial iridescence that characterize all the Great Lakes forms of Leu- 

 cichthys. Preserved specimens show moderate pigmentation on the back but 

 heavier pigment on the cranium. The prenarial region is often nearly black, as is 

 the tip of the mandible. The preorbital area and the maxillary also are always pig- 

 mented. The dorsal and caudal fins are widely margined with smoky, the hue 

 being deepest on the short rays of the caudal. The paired fins and the anal always 

 show more or less of pigment. 



No breeding fish have been seen, and it is not known that pearl organs are 

 developed in the breeding season, but it is likely that they are. 



VARIATIONS 



Racial variations. — Very few specimens have been examined, and it is not pos- 

 sible to state from the material at hand whether there are races within the species. 



Size variations. — Sixteen of the forty-four specimens are less than 300 milli- 

 meters in length. A comparison of these with the larger fish indicates that the head, 

 eye, maxillary, and paired fins become proportionally smaller with growth and the 

 body depth increases proportionally. The figures follow : 

 L/H: 



H/E: 



H/S: 



Large fish, (3.9) 4-4.1 (4.5). 

 Small fish, (3.8) 3.9-4 (4.1). 



Large fish, (4.4) 4.6-4.8 (5.2). 

 Small fish, (3.8) 4.2-4.4 (4.5). 



Large fish, (3.3) 3.5-3.8 (4). 

 Small fish, (3.5) 3.7-3.8 (4). 



H/M: 



Large fish, (2.5) 2.7-2.8 (3.1). 

 Small fish, 2.5-2.8. 



Pv/P: 



Large fish, (1.5) 1.7-1.8 (1.9). 

 Small fish, (1.4) 1.5-1.6 (1.8). 

 Av/V: 



Large fish, 1.4-1.6 (1.7). 

 Small fish, (1.2) 1.4-1.5 (1.6). 

 L/D: 



Large fish, (3) 3.3-3.6 (3.7). 

 Small fish, (3.5) 3.8-4 (4.1). 



All but one of the specimens under 300 millimeters have been found sexually 

 immature. 



COMPARISONS 



A discussion of the differences between nipigon and the other species of Leu- 

 cichthys occurring in Lake Nipigon is given under the heading "Comparisons" in 

 the accounts of these species. 



GEOGRAPHICAL DISTRIBUTION 



The data from my nets and those of the University of Toronto investigators set 

 during the summers of 1921, 1922, 1923, and 1924 are given in Table 79 and platted 

 on the lake chart in Figure 2 and indicate that this species is found throughout 

 Lake Nipigon. 



BATHYMETRIC DISTRIBUTION 



Very little is known about the depth preferences of nipigon. The data that 

 we have are obtained, for the most part, from the use of nets that were of too large 



84 Ten specimens. 



