GENUS CHASMISTES JORDAN 



Head large, bioad and flattish above, the sides vertical; eye 

 small, high up, and rather posterior; mouth very large, terminal, 

 the lower jaw in the closed mouth being very oblique; lower 

 jaw long and strong, more than half length of head, its tip, 

 when the mouth is closed, about on a level with the eye; upper 

 jaw very protractile; upper lip thin and nearly smooth; snout 

 usually elevated above rest of head; the premaxillary spines gene- 

 rally forming a conspicuous nose; lower lip moderate, consisting 

 of a broad flap on each side of the mandible, reduced to a nar- 

 row rim in front, the surface of the lip nearly smooth, without 

 papillse; nostrils large; fontanelle well developed; gillrakers simple, 

 fringe-like; air-bladder in 2 parts. Species of rather large size, 

 inhabiting the Great Salt Lake Basin and the Klamath Lakes of 

 southern Oregon. 



Six species are recognized, only 4 of which seem to be of 

 any commercial importance. 



a. Scales moderate, 60 to 6s in the lateral line. 



/'. Scales 9-63-8; dorsal usually 11; nose prominent; Horns, 54 



aa. Scales small, 7s to 8s in the lateral line. 



c. Snout prominent, premaxillary spines strongly protruding, form- 

 ing a prominently projecting snout; stomias, 5s 



cc. Snout not prominent, premaxillary spines not forming a pro- 

 minent hump. 



(/. Scales 12-7S- 11; brevirostris, SS 



iid. Scales 13-80-12 ; copei, s6 



June Sucker of Utah Lake 



Chasmistcs lioiiis Jordan 

 Known only from Utah Lake, where it is exceedingly abundant. 



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