GREAT LAKES COREGONIDS 



389 



COMPARISONS 4t> 



Zenithicus approaches closely only reighardi and alpenx. It is distinguishable 

 from typical reighardi by the longer snout and maxillary, smaller eye, somewhat 

 longer head, and more gill rakers on the first branchial arch. Fish of the northern 

 race of reighardi, however, usually show nearly as long a snout, and the maxillary 

 and head differences are not so pronounced as between zenithicus and typical~m<7- 

 hardi. A numerical expression of these characters for these fish follows: 



Gill rakers on the first branchial arch: 



zenithicus, (35) 38-42 (44), with 74 per cent more than 38. 



reighardi, north, (30) 34-37 (43), with 15 per cent more than 38. 



reighardi, south, (31) 35-38 (43), with 13 per cent more than 38. 

 H/E: 



zenithicus, (4) 4.2-4.5 (5), with 74 per cent more than 4.2. 

 reighardi, north, (3.7) 4-4.3 (4.6), with 16 per cent more than 4.2. 

 reighardi, south, (3.6) 3.9-4.2 (4.4), with 5 per cent more than 4.2. 

 H/M: 



zenithicus, (2.2) 2.4-2.6 (2.8), with 23 per cent more than 2.5. 

 reighardi, north, (2.3) 2.5-2.7 (3), with 73 per cent more than 2.5. 

 reighardi, south, (2.5) 2.6-2.8 (2.9), with 97 per cent more than 2.5. 



H/S: 



zenithicus, (3.2) 3.4-3.7 (4), with 30 per cent more than 3.6. 

 reighardi, north, (3.2) 3.4-3.8 (4.3), with 40 per cent more than 3.6. 

 reighardi, south, (3.5) 3.6-4 (4.4), with 83 per cent more than 3.6. 

 MS/E: 



zenithicus, (2.6) 2.8-3.1 (3.2), with 97 per cent more than 2.6. 

 reighardi, north, (2.2) 2.5-2.7 (3.1), with 46 per cent more than 2.6. 

 reighardi, south, (2.2) 2.4-2.6 (2.8), with 5 per cent more than 2.6. 

 L/H: 



zenithicus, (3.9) 4-4.3 (4.5), with 7 per cent more than 4.3. 

 reighardi, north, (3.9) 4.1-4.4 (4.7), with 26 per cent more than 4.3. 

 reighardi, south, (4) 4.2-4.5 (4.8), with 48 per cent more than 4.3. 



Reighardi has a wider body, deeper head, shorter pectorals, and more heavily 

 pigmented premaxillaries, maxillary, and mandible, and there is often more pigment 

 on the body and abdominal fins. (See also fig. 11.) 



Discussion of the differences between zenithicus and johannx and alpense are 

 given on pages 351 and 364. 



Zenithicus is easily distinguished from nigripinnis by the fewer gill rakers, 

 which in the former are not more than 44 and in the latter seldom less; by its shal- 

 lower and more elongated head in side view, as contrasted with the deep, blunt one 

 of nigripinnis; by its less body depth, which in side view is usually elliptical in the 

 first and ovate in the other; by the mandible, which in zenithicus is not conspicuously 

 pigmented and is included in the upper jaw and in nigripinnis is usually heavily 

 pigmented and equal to or longer than the upper jaw; and by the much paler and 

 shorter paired fins. The comparative figures for fin length follow: 



Pv/P: 



zenithicus, (1.7) 2-2.2 (2.6), with 90 per cent more than 1.8. 

 nigripinnis, (1.5) 1.6-1.8 (2.2), with 18 per cent more than 1.8. 

 Av/V: 



zenithicus, (1.2) 1.4-1.6 (2), with 64 per cent more than 1.4. 

 nigripinnis, 1.2-1.5 (1.6), with 28 per cent more than 1.4. 



" Figures given under this section for proportions are based on specimens 200 millimeters or more in length, except artedi where 

 the limit is 225 millimeters. Counts are given for specimens of all sizes. 



