240 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY - IV. 



Head conic, the profile steep, the muzzle short and rather pointed. 

 Mouth small, oblique, the jaws nearly equal, the upper lip on the level 

 of the lower part of the pupil, the maxillary scarcely Teaching to front 

 of eye; isthmus very narrow; preorbital nearly as deep as long. Eye 

 small, anterior, 5 in head. Fins low. Dorsal fin opposite ventrals, 

 nearer caudal than snout; caudal tin short, little forked, scarcely broader 

 than the very deep caudal peduncle, the spines of the caudal vertebra' 

 very strong. Scales large, rather closely imbricated, their exposed sur- 

 faces rather deeper than long; 2G scales before dorsal. Lateral line 

 decurved. Color brownish; sides white; young spotted above; scales 

 everywhere with dark dots; fins plain. Head 4 J; depth 3. D. 8; A..S; 

 scales 9-5G-7 ; teeth 2, 5-4, 2. L. 12 inches. Elvers of California : very 

 abundant. One of the most peculiar of our Cyprinidir, but hardly const i- 

 tuting A distinct genus. 



(Lavinia cr<m?mHf?rt Baird & Girard, Proc. Acad. Nat. Sci. Phila. 1^5-1, 137 (August |: 

 Siboma crassicauda Girarcl, Proc. Acad. Nat. Sci. Phila. 185G, 208, and IT. S. Pac. ]{. 

 R. Surv. Fisb. 296: Leuclscus crassicaada Gliuther, vii, 243: Lcttcisaus gihboxnn Ayres, 

 Daily Placer Times and Transcript, May 30, 1854: Lavinia yibboxa Ayu-s, Proc. c'al. 

 Acad. Sci. 1854, 20.) 



** Teeth with evident grinding surface.* (SquaUus.~) 



c. Robust species; depth 3 to 3^ in length ; lateral Hue less than GO. 



395. S. rhomaleus Jor. &. Gill.. 



Body very robust, elevated anteriorly, the sides compressed, although 

 the back is very broad. Head broad, the profile concave as seen from 

 the side, the iuterorbital space flattish, scarcely raised above the eye. 

 Snout broad, elevated at tip, premaxillary on the level of pupil. Mouth 

 very oblique, the mandible much projecting, maxillary reaching front of 

 eye. Eye small, anterior, 1 : | in snout, 7 in head; isthmus very narrow. 

 Scales large, subequal, broadly exposed, firm. Lateral line decurved. 

 Dorsal nearly median, inserted directly over ventrals. Caudal evenly 

 forked, the peduncle long and deep. Pectorals short, extending thive- 

 fifths the distance to ventrals, ventrals about to vent. Lower tins short. 

 Color blackish; everywhere dark. Head iU ; depth .">.]. 1). 0; A. 8; 

 scales 10-5")-."); teeth 2, .">-!, 2, short and stout, one of them with grinding 

 surface. L. 12 inches. I T t ah Lake. Oueof the largest and best marked 

 species. 



(Jordan & Gilbert, Pro.-, t:. S. Nat. Mus. 1880, 



A variable character in this grmip. 



