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 upj)er lip on the level 

 of the lower part of the pupil, the maxillary scarcely reaching- to front 

 of eye; isthmus very narrow; x^^^orbital nearly as deep as long. Eye 

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

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

 than the very deep caudal peduncle, the spines of the caudal vertebrjc 

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

 faces rather deeper than long; 26 scales before dorsal. Lateral line 

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

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

 scales 9-56-7 ; teeth 2, 5-4, 2. L. 12 inches. Elvers of California ; very 

 abundant. One of the most peculiar of our Gyprinidw, but hardly consti- 

 tuting a distinct genus. 



(Lavinia crasskattda Baird «&Gu-ard, Proc. Acad. Nat. Sci. Phila. 1854, 137 (August): 

 Siboma crassicauda Girard, Proc. Acad. Nat. Sci. Phila. 1856, 208, and U. S. Pac. R. 

 R. Surv. Fisli. 296: Leuciscus crassicauda Gliutlier, vii, 243: Leuciscus gibbosus Ayres, 

 Daily Placer Times and Transcript, May 30, 1854: Lavinia gihbosa Ayres, Proc. Cal. 

 Acad.Sci. 1854, 20.) 



** Teeth with evident grinding surface.* {Squalius.) 



c. Robust species; depth 3 to S^- in length; lateral line less than 60. 



395- S. rhomaleiis Jor. & Gilb. 



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 flatfish, 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, fiBm. Lateral line decur\e(l. 

 Dorsal nearly median, inserted directly over ventrals. Caudal evenly 

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

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

 Color blackish; everywhere dark. Head 3i; depth 3^. D. 0; A. 8; 

 scfiles 10-55-5 ; teeth 2, 5-4, 2, short and stout, one of them with grinding 

 surface. L. 12 inches. Utah Lake. One of the largest and best marked 

 species. 



(Jordan & Gilbert, Proc. U. S. Nat. Mus. 1880, 461.) 



* A variable character in this group. 



