GREAT LAKES COREGONIDS 



349 



about 25 fathoms on July 3, 1906." Counts of certain multiple parts and propor- 

 tional lengths for this specimen are shown in Table 17 and are repeated in the text 

 description that follows. 



Leucichthys johannse of Lake Michigan 



The chub is moderate in size, seldom longer than 3 decimeters (12 inches), with 

 a maximum weight of about 13^ pounds. The fish is roughly fusiform in shape, 

 moderately compressed, and elongate. The greatest depth is just in front of the 

 dorsal and usually comprises 22 to 27 per cent of the total length. The width is 

 about 48 to 53 per cent of the depth. The anterior dorsal profile rises rapidly and 

 in nearly a straight line for about two-thirds the distance from the tip of the pre- 

 maxillaries to the dorsal and continues to the dorsal in a curve with only a slight 

 upward trend. From the insertion of the dorsal the contour slopes into the caudal 

 peduncle in a more or less straight line. The ventral profile from the tip of the 

 snout to the caudal peduncle is rather uniformly curved. The head is relatively 

 long and of little depth, rather acutely triangular in side view. Its length is con- 

 tained 4.2 [(3.8) 4-4.2 (4.4)] 4 times in the total length. The snout likewise is elon- 

 gate, narrow, and acute in side view, and is contained 3.4 [(3.2) 3.3-3.6 (4)] 5 times 

 in the head length. The premaxillaries usually are little or not at all pigmented 

 and are oblique in position, meeting the horizontal axis of the head at an angle of 

 50° to 60°. The maxillary seldom is pigmented and never extends to the center of 

 the eye. The lower jaw is moderately developed and usually equal to the upper, 

 though often longer or shorter. The eye is moderate in size and is contained 4.5 

 [(4) 4.4-4.6 (4.9)] times in the length of the head. The gill rakers on the first bran- 

 chial arch number 10 + 19 [(9) 10-12 (14) + (16) 17-20 (22)] = (26) 27-32 (36). 6 

 Scales in the lateral line number 82 [(74) 80-90 (95)]. Rows of scales around the 

 body in front of the dorsal and ventrals number 41 [(38) 41-44 (46)], 7 in front of 

 the adipose and anus 33 [(31) 33-37 (38)], 7 and around the caudal peduncle at its 

 commencement 26 [(22) 24-26 (27)] 7 . 



The dorsal rays are 10 [9-10 (ll)]; 8 anal rays 12 [(10) 11-13 (16)] ; 8 pectoral 

 rays 17 [(14) 16-17 (20)]; ventral rays 11 [11-12]. 9 The length of the pectoral fin 

 is contained 2 [(1.5) 1.6-1.8 (2.1)] times in the distance from the pectorals to the 

 ventrals. The dorsal margin of the distal third of the pectoral usually is strongly 

 decurved. The length of the ventrals is contained 1.5 [(1.1) 1.2-1.5 (1.6)] times in 

 the distance from their origin to the origin of the anal. 



The color in life is silvery, with a more or less faint pinkish to purplish iridescence, 

 which is strongest above the lateral line and absent on the belly. Close examina- 

 tion reveals a pale slaty bluish to pea green on the back below the silvery layer. 

 This color is most pronounced in front of the dorsal. It changes to blue-green halfway 

 to the lateral line, and that color continues to the white belly. The slaty tone is 



* The figures in brackets, unless otherwise stated, are based on an examination of 74 specimens, ranging in length from 212 to 

 288 millimeters. 



* Forty-seven specimens. 



■ One-hundred and twenty-two specimens. 



* Thirty specimens. 



* Forty-seven specimens. 



* Ten specimens. 



