378 



BULLETIN OF THE BUREAU OF FISHERIES 



Leucichthys zenithicus of Lake Superior 



The short-jawed chub does not attain great size. The largest individual I have 

 ever seen measured only 332 millimeters, and few specimens larger than 300 milli- 

 meters have been taken. The body is moderately compressed, elongate, and, as 

 seen from the side, tapers smoothly and regularly to the head and tail from the deepest 

 portion of the body, which is at the front of the dorsal. The depth at this point is 

 quite variable and ranges in adults from 19 to 27 per cent of the length, with the 

 usual range between 21 and 24 per cent. The width is about 50 to 55 per cent of the 

 depth. The head, which is of relatively little depth, is contained 3.7 [(3.6) 3.8-4.1 

 (4.4)] 30 times in the total length. The dorsal margin of the head, not including the 

 premaxillaries, is more or less straight. The snout is long and is contained 3.5 [(3.1) 

 3.3-3.6 (4)] times in the head length. It is truncated in side view, due to the 

 nearly vertical position of the premaxillaries, which usually make an angle of 60° to 

 70° with the horizontal axis of the head. The maxillary likewise is long, is contained 

 2.5 [(2.1) 2.3-2.5 (2.7)] times in the head, and except in rare cases is more or less 

 pigmented. The lower jaw usually is immaculate or faintly pigmented and included 

 within the upper in about three-fourths of all the specimens seen. The eye is moderate 

 in size and is contained 4.6 [(3.9) 4.2-4.6 (5.1)] times in the head. The gill rakers on 

 the first branchial arch number 17 + 28 [(13) 14-16 (17) + (21) 24-26 (29) = (32) 

 39-43 (46)]. 31 



The scales in the lateral line number 74 [(69) 74-84 (90)]. 32 Rows of scales 

 around the body just in front of the dorsal and ventrals number 40 [(37) 39-42 (45)]; 33 

 just in front of the adipose and anus 34 [(31) 32-34 (35)]; 34 around the caudal peduncle 

 24 [(22) 23-25 (26)]. 34 There are 10 [(10-11)] 35 dorsal rays, 12 [(10) 11-12 (13)] 35 

 anal rays, 12 [11-12] 35 ventral rays, and 16 [(15) 16-17 (18)] 35 pectoral rays. The 

 dorsal margin of the pectorals usually is more or less straight, at least not often 

 sharply decurved. The pectoral length divided into the pectoral-ventral distance 

 is contained 1.6 [(1.3) 1.6-2 (2.4)] times. The length of the ventrals is contained 

 1.3 [(1) 1.3-1.6 (1.9)] times in the distance from their insertion to that of the anal. 

 The sum of the greatest depth of the head and the length of the base of the anal 



fin divided by the sum of the snout and maxillary length - — m + S^ equals 1.52 



[(1.30) 1.45-1.55 (1.75)]. 



The color in life is silvery, as in the other species of Leucichthys. The color is 

 like that described for the chub on page 349, except that the dorsal surface is dark 

 blue green to pale pea green. The color is obscured everywhere by somewhat heavier 

 pigmentation, which is most pronounced around the free margins of the scales. 

 There is a distinct purplish iridescence, most intense above the lateral line|!and 

 paling gradually into the colorless belly. In addition to the patches of green in the 

 frontal bones noted in the description of the chub, there are often two streaksfof 



3 <> The figures in brackets, except where otherwise stated, are based on an examination of 787 specimens, ranging in length from 

 200 to 332 millimeters. 



31 Eight hundred and eighty-three specimens. 



32 Nine hundred and fifty-six specimens. 



33 Two hundred specimens. 

 31 Twenty specimens. 



33 Forty specimens. 



