358 



BULLETIN OF THE BUREAU OF FISHERIES 



L/H: 



johannse, (3.4) 3.8-4.1 (4.3), with 20 per cent more than 4. 

 zenithicus, (3.9) 4.1-4.3 (4.5), with 77 per cent more than 4. 

 Pv/P: 



johannse, (1.3) 1.5-1.8 (2.1), with 10 per cent more than 1.8. 

 zenithicus, (1.6) 1.9-2.1 (2.3), with 82 per cent more than 1.8. 

 Av/V: 



johannse, (1) 1.2-1.4 (1.6), with 11 per cent more than 1.4. 

 zenithicus, (1.2) 1.5-1.6 (1.8), with 77 per cent more than 1.4. 



Johannse. differs from nigripinnis in about the same manner as the chub of 

 Lake Michigan differs from the Lake Michigan blackfin. They differ less, however, 

 in the degree of pigmentation of the premaxillaries in Lake Huron. There is some 

 pigment on the premaxillaries of johannse, but they average much paler than in 



nigripinnis. 



Only small johannse are comparable with Tciyi, for Tciyi in Lake Huron is not 

 known to grow large. Johannse may be separated from Tciyi by the fewer gill rakers, 

 smaller eye, and less pigmentation. The number of gill rakers on the first branchial 

 arch in johannse is (25) 27-31 (35), in Tciyi (34) 36-40 (44); H/E for johannse is (3.6) 

 4-4.3 (4.5), with 72 per cent more than 4, and for Tciyi (3.3) 3.6-3.8 (4). The maxil- 

 lary in Tciyi is almost always pigmented over at least half its surface, while in johannse 

 it is almost always white. Kiyi has also, on the average, longer paired fins, and 

 the mandible is frailer, darker, and usually longer. The state of development of the 

 ova will aid in separating females at certain seasons, for johannse spawns at least a 

 month earlier. 



Johannse is absolutely separable from artedi by the number of gill rakers, which 

 in the former are not known to number more than 35 and in the latter not less than 

 40; and by the body shape, which is elliptical in side view only in artedi. Johannse 

 also has a longer, more attenuated head, longer snout, maxillary, and paired fins, 

 and a smaller eye. The maxillary is always pigmented in artedi and seldom shows 

 pigment in johannse, and the body is generally much darker throughout in the former. 

 The state of development of the sex organs also is an aid in separating the two, as 

 johannse spawns in September and artedi in November. The proportional characters 

 referred to above are compared below: 

 L/H: 



artedi, (4) 4.3-4.6 (5), 17 with 80 per cent more than 4.2. 

 johannse, (3.4) 3.8-4.1 (4.3), with 1 per cent more than 4.2. 

 H/E: 



artedi, (3.7) 3.9-4.3 (4.7), with 19 per cent more than 4.2. 

 johannse, (3.9) 4.3-4.8 (5.3), with 87 per cent more than 4.2. 

 H/S: 



artedi, (3.5) 3.7-4 (4.3), with 82 per cent more than 3.6. 

 johannse, (3.1) 3.3-3.5 (3.6). 

 Pv/P: 



artedi, (1.7) 2-2.2 (2.6), with 72 per cent more than 1.9. 

 johannse, (1.3) 1.5-1.8 (2.1), with 2 per cent more than 1.9. 

 Av/V: 



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

 johannse, (1) 1.2-1.4 (1.6), with 11 per cent more than 1.4. 



The differences between johannse and hoyi are given on page 461. 



" Figures for artedi do not include the manitoulinus form. 



