GREAT LAKES COREGONIDS 



317 



bloated, sometimes even burst, and because the softness of the flesh of the individuals 

 of the species renders it very difficult to preserve the shape properly during the period 

 of collection. These characters also change proportionally during the growth of the 

 individual, all young fish of the group having frailer bodies than the adults. The 

 relative width and depth of the body, therefore, is variable for each species, and for 

 none of the species is it a distinguishing character. In certain species the body 

 depth varies relatively much more than in others. In the case of the lake herring 

 (L. artedi) the several varieties are differentiated sharply by the relative depth of the 

 body. In the typical artedi L/D is higher, on the whole, than for any other coregonid 

 in the basin, while for the albus type occurring in the same lake it may be as low as 

 or lower than that of any other coregonid. The races of reighardi, nigripinnis, 

 and clupeaformis also are differentiated in part by variation in this character. 



Scales in the Lateral Line 



The number of scales in the lateral line is variable within a species and even 

 within a race. It may be seen from Table 7 that the extremes are much the same 

 for the various species in each lake. In most of the lakes quadrilaterale, with the 

 maximum number of scales, is more or less distinctly separated only from Jioyi, 

 which has the smallest number; though in Lake Nipigon, where most of the species 

 of Leucichthys have relatively few scales, it is probable that the scale count usually 

 would be a generic distinction between Leucichthys and Prosopium. However, 

 the usual number of scales is rather different for the various coregonids in each lake. 



The usual number of scales also is more or less different for most of the geo- 

 graphically separated forms of each species. As has been pointed out above, all the 

 races of Leucichthys occurring in Lake Nipigon have fewer scales on the average than 

 those from other lakes, except the race of the species Tioyi, which tends to have more 

 than its relatives. The Huron forms of johannse, nigripinnis, Tciyi and quadri- 

 laterale, the Superior form of Tciyi, and the Erie form of clupeaformis also seem to 

 have somewhat fewer scales than the Michigan forms of these species. The sub- 

 species of artedi may differ conspicuously in the character, as is illustrated by the 

 manitoulinus form of Huron and the albus subspecies of Superior and Erie. 



Scale Rows 



The number of longitudinal scale rows around the body also is variable within a 

 species and within a race. Below are given the comparative values for the forms of 

 Lake Michigan. A similar table for the other lakes would show about the same rela- 

 tion between the counts. 



Species 



Number in front 

 of dorsal and 

 ventrals 



Number in front 

 of adipose and 

 anal 



Number around 

 caudal 

 peduncle 



Leucichthys: 



johannse 



alpenae. 



zenithicus-. 



reighardi 



nigripinnis 



kiyi... 



hoyi.. 



artedi 



nipigon ' 



Coregonus clupeaformis.. 



Prosopium quadrilaterale 



(38) 41-44 (46) 



(40) 41-43 (45) 

 40-42 (46) 



(38) 40-43 (46) 



(41) 42-44 (45) 



(39) 41-44 (46) 



(38) 40-42 (44) 



(39) 43-46 (49) 

 (41) 43-45 

 (46) 48-50 (52) 



(40) 42-15 (46) 



(31) 33- 

 (30) 33 

 (30) 32- 



(30) 32- 



(32) 33- 

 (32) 33 



(31) 32- 



(32) 34- 

 (32) 33 

 (36) 37- 

 (31) 33- 



-37 (38) 

 -35 (36) 

 -34 (36) 

 ■35 (39) 

 ■35 (36) 

 ■35 (37) 

 ■34 (35) 

 ■37 (38) 

 -34 (35) 

 -39 (40) 

 -35 (36) 



(22) 24- 



(23) 24- 

 (23) 24- 



22- 

 (23) 24 

 (23) 24 



(22) 23 



(23) 24- 



(23) 24- 

 25- 



(24) 25- 



-26 (27) 

 -26 (27) 

 -25 (26) 

 -24 (26) 

 -26 (27) 

 -25 (26) 

 -25 (26) 

 -26 (27) 

 -25 (27) 

 ■27 (28) 

 -27 (28) 



Lake Nipigon specimens. 



