358 ADDBITDA. 



2. S. irideus, Gihhoas. PAcrPic Bkook Teout. Torm 

 stout; head short, bluntish; mouth small, the maxillarj 

 scarcely reaching beyond eye. Streams W. of Sierra 

 Nevada. {/S. newberrii, Grd., S. masoni, Suckl.) 



aa. Scales small, in 165—205 rows. 



6. Caudal somewhat forked; head small, conical, rather 

 pointed. 



3. S. isuppiich, Rich. Black Teout of Lake Tahoe, 

 Rather slender; mouth moderate; opercle prolonged 

 backwards; scales in 180 rows. Streams W. of Sierra 

 Nevada. 



hb. Caudal double-rounded; head heavy, shortish, convex. 



4. S. spilurus, Cope. Big-Mouthbd Teout. Mouth 

 very large, the maxillary reaching much beyond eye; 

 opercle not specially prolonged; black spots most numer- 

 ous posteriorly. Rocky Mountain region, Wyoming to 

 Arizona. 



Ya.T. p/euriti'cus. Cope. Scales small, in 300 rows; 

 head carinate. Generally distributed. 



Var. spilurus I (Cope). Scales larger, in 170 rows; 

 heud strongly convex. Utah to Colorado, etc. 



f Hyoid bone with an elongate band of small teeth (easily 

 scraped ofl' by careless observers). 

 c. Head large and long — acuminate; hyoid teeth weak; cau- 

 dal somewhat forked. 



5. S. henshawi, G. & J. {sp.n.) Silver Teout of Lake 

 Tahoe. Head little carinate; body elongate, not much 

 compressed; scales in 160 — 184 rows. Streams of Cal. 



ee. Head comparatively short and blunt ; hyoid teeth rather 

 strong; caudal less forked. 



6. S. stomias. Cope. Scales in 200 rows; head broad 

 and flat. Upper Missouri. 



