500 



BULLETIN OF THE BUREAU OF FISHERIES 



with Lake Erie specimens, except that the eye regularly may be a trifle larger in the 

 former. 



The color in life is like that of the Erie form, except that the deep blue green is 

 the commonest shade. As in Lake Huron, fish with pale backs occur in any school. 

 The body, especially the back and the cranium, is also more heavily pigmented as 

 a rule. The fins average a trifle darker, too, except possibly the ventrals and the anal. 



Pearl organs are developed in the species, but the specimens obtained in Thunder 

 Bay on November 25, 1922, were so rubbed in transit that the extent of the develop- 

 ment of nuptial adornment could not be ascertained. It is probably no different 

 from that described for the species in the other lakes. 



VARIATIONS 



Racial variations. — There are two types of herring in Lake Superior, as there 

 are in Lake Erie — the elongated, subterete form and the deeper, more compressed 

 one. The latter closely resembles the common Erie type and occurs commonly, 

 so far as is known, only in the shallow, warm bays at the north end of the lake. 

 (Hankinson, 1916, PI. XXVIII, A, gives a photograph of a specimen taken'off White- 

 fish Point, Mich., on the south shore.) These bays, however, are connected freely 

 with the main lake, and the long, slender type is therefore also of common occurrence 

 in their waters, as are, of course, intergrades between the two. In fact, typical alius 

 have not been found as commonly as the others, as will appear from the figures below. 

 No careful study has been made of the races of herring in this or any other area, but 

 in comparing 135 specimens from the north bay region with 118 specimens taken in 

 the main lake on the eastern and southern shores, 57 certain tendencies of variation 

 are indicated, which are expressed in some measure by the following: 



Lateral-line scales: 



North bays, (72) 79-93 (100), with 19 per cent less than 80. 



Lake, (76) 84-92 (105), with 1 per cent less than 80. 

 Pv/P: 



North bays, (1.6) 1.8-2.2 (2.6), with 30 per cent less than 2.0. 

 Lake, (1.8) 2.1-2.3 (2.5), with 9 per cent less than 2.0. 

 Av/V: 



North bays, (1.5) 1.6-1.8 (2), with 16 per cent less than 1.6. 

 Lake, (1.3) 1.6-1.9 (2), with 6 per cent less than 1.6. 



The figures show that the range is about the same for both groups, but this is 

 due to the fact that the "north bays" group is made up of all fish that have been 

 collected on the north shore, regardless of whether they probably were regular in- 

 habitants of the bays; and the figures are interesting only inasmuch as they show 

 tendencies of the bay fish to vary in the direction of the common Erie type. In 

 Table 74 the first five specimens in the group of individuals 225 millimeters or more 

 in length, four of them albus and one artedi, are from the north bays; the other five 

 are artedi from the open lake. These two groups also show a difference in those 

 characters that have been mentioned above and indicate further that the northern 

 fish are deeper bodied. 



« Neither group contains specimens assorted according to size, but the proportion of 3 pecimens under 225 millimeters in length 

 is about the same for both. 



