GREAT LAKES COREGONIDS 



423 



COMPARISONS 



Nigripinnis resembles small Myi and artedi most closely. 



Small nigripinnis can be distinguished from Myi probably only by the usual 

 absence of black on the ventrals and the lighter pigmentation of the other ventral 

 fins and by the fewer gill rakers, which in the former are (40) 46-50 (52) and in the 

 latter (34) 36-40 (44), with 24 per cent more than 39. The state of development of 

 ova in females might also serve to aid in separating the species at certain seasons, as 

 nigripinnis spawns probably at least a month later than Myi. 



From artedi, nigripinnis is distinguished always by the body shape, as seen 

 from the side, and the softer, more oily flesh. The body of the blackfin typically is 

 deepest anteriorly, so as to be somewhat ovate in side view, and in the herring is 

 more nearly elliptical. The common form of artedi has a smaller head and maxillary 

 and shorter paired fins, but none of these differences hold for the Cutler race. A com- 

 parison of these characters follows: 

 L/H: 



nigripinnis, (3.7) 4-4.2 (4.4). 



artedi, (4) 4.3-4.6 (5), with 57 per cent more than 4.4. 

 H/M: 



nigripinnis, (2.4) 2.5-2.6 (2.7), with 16 per cent more than 2.6. 

 artedi, (2.6) 2.8-3 (3.3), with 96 per cent more than 2.6. 

 Pv/P: 



nigripinnis, (1.2) 1.4-1.7 (1.9), with 1 per cent more than 1.8. 

 artedi, (1.7) 2-2.2 (2.6), with 92 per cent more than 1.8. 

 Av/V: 



nigripinnis, (I) 1.1-1.4 (1.6), with 1 per cent more than 1.5. 

 artedi, (1.4) 1.6-1.8 (2.1), with 90 per cent more than 1.5. 



The fins of nigripinnis are, as a rule, much darker than of any artedi except 

 those around Cutler. However, there is little occasion for confusing the two species 

 in the field, as only stragglers of artedi are found off the shoals and nigripinnis is 

 found rarely at depths of less than 60 fathoms. 



Nigripinnis is compared with the other species of Leucichthys occurring in Lake 

 Huron under the heading "Comparisons" in the accounts of these species. 



GEOGRAPHICAL DISTRIBUTION 



Table 42 contains all my data on the occurrence of the blackfin in Lake Huron. 

 Figure 5 shows these data plotted on the chart of Lake Huron. 



Lake Enron proper. — The records from the chub nets show the blackfin to occur 

 in the same localities in the lake as do the other species of chubs. The same con- 

 clusion regarding distribution is warranted for this form, therefore, namely, that it 

 ranges throughout the deeper waters of Lake Huron. 



North Channel. — No specimens have been seen from the North Channel. The 

 fishermen report chubs from this region (see p. 373), but they are not blackfins, 

 according to these reports. Most fishermen are able to distinguish the blackfin 

 from the other three species of chubs, and it is reasonably sure, therefore, that these 

 reports are correct. 



14 Figures given in this section are for all collected specimens except those of artedi, which are given for those specimens 225 

 millimeters or more in length, not including specimens of manitoulinut. 



94995—29 9 



