The Whitefishes 



/'. Jaws toothless or nearly so; scales large; maxillary short and 

 broad, with a broad supplemental bone. 



c. Premaxillaries broad, with the cutting edge nearly vertical or 



directed backward, the lower jaw short and more or less 

 included; cleft of mouth short; Coregonus, 1 17 



cc. Premaxillaries with the cutting edge nearly horizontal and 

 directed forward; lower jaw long, projecting beyond tho 

 upper; cleft of mouth long; Argyrosonnts, 130 



bb. Jaws, vomer, palatines, and tongue with bands of teeth; 

 maxillary very long; lower jaw prominent; anal fm elongate; 

 scales moderate ; Stenodus, 142 



Salmonince : 



na. Mouth deeply cleft, the long lower jaw articulating with the 

 quadrate bone behind the eye; dentition strong and com- 

 plete; conical teeth on jaws, vomer, and palatines; tongue 

 with 2 series of strong teeth; scales small. 



d. Anal fin elongate, of 14 to 17 rays; Oncorhvnchus, 143 



dd. Anal fin short, of 9 to 12 developed rays. 



e. Vomer flat, its toothed surface plane; teeth on shaft of vomer 



in alternating rows or in one zigzag row, and placed 

 directly on the surface of the bone, not on a free crest. 

 Species black-spotted ; Salmo, 1 59 



ee. Vomer boat-shaped, the shaft strongly depressed and without 

 teeth; spotted with gray or red. 



/. Vomer with a raised crest, armed with strong teeth, extend- 

 ing backward from the head of the bone, free from its 

 shaft, hyoid bone with a broad band of strong teeth. 

 Species spotted with gray, without bright colours; 



Cristivomer, 203 



ff. Vomer without a raised crest, only the head being toothed; 

 hyoid bone with very weak teeth or none. Species red- 

 spotted, the lower fins with bright edgings; Salvelinus, 206 



GENUS COREGONUS ART EDI 

 The Whitefishes 



Body compressed; head more or less conic, compressed, the 

 snout more or less projecting beyond the lower jaw; mouth 

 small, the maxillary short, not extending beyond the orbit, with 

 a well-developed supplemental bone; teeth extremely minute, if 

 present; scales moderate, thin, cycloid, rather firm; caudal fin 



117 



