224 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



anterior ; premaxillaries protractile ; fold of lower lip not crossing the 

 symphysis ; lower jaw trenchant, without horny covering ; no barbels. 

 Gill rakers short. Pharyngeals strong. Teeth 3-3, of the Mylochilus 

 type, more or less cylindrical, with rounded grinding surfaces, ijosterior 

 more slender and subcorneal. {<Tzh-<K, stump ; ot^wv, tooth.) 



352. S. sigiiifer Garman. 



Dorsal and ventral outlines similar. Eye large, longer than snout. 

 Mouth oblique, the maxillary not reaching front of eye. Lower jaw the 

 longer. Pectorals not reaching ventrals, the latter to anal. Brown; 

 silvery below ; a broad brown lateral band, bordered above by a nar- 

 row silvery line. Head 3|; depth 3|. J). 8; A. 8; scales G-35-2 ; 

 ^' teeth 3-3, stout, stump -like, with convex summits." Lago de Parras, 

 an isolated lagoon in Coahuila, Mexico. (Garman.) 



(Garmau, 1. c. 90.) 



98.— MYLOCHILUS Agassiz. 



(Mylocheilus Agassiz, Amer. Journ. Sci. Ai'ts, 1855, 229: type Mylocheihts lateralis 

 Agassiz = Leucisctis caurlnus Rich.) 



Body elongate, not elevated, little comi^ressed. Head rather short, 

 conic, somewhat pointed. Mouth rather small, little oblique, the lower 

 jaw included ; maxillary with small barbel at its end ; upper jaw pro- 

 tractile. Scales moderate not closely imbricated. Lateral line de- 

 curved. Dorsal fin beginning nearly opposite ventrals. Caudal fin with 

 the rudimentary rays little developed. Anal basis short. Litestinal 

 canal about as long as body. Teeth 2, 5-5, 2, or 2, .')-4, 2, two or three 

 of those in the main row molar, much enlarged, blunt and truncate 

 above. (A third deciduous row sometimes jiresent, according to Girard, 

 in this genus and in MylopJiarodon; we have seen nothing of the kind.) 

 Size large. {/t'jX(K, grinder; /stAo?, lip.) 



353. M. cauriiiiis (Ricliardson) Gid. — Columbia Chub. 



Eye large, shorter than snout, 5 in head ; interorbital space broad, 

 convex. Mouth horizontal or nearly so, the maxillary not reaching the 

 front of the eye ; suborbital bones wide ; j^reorbital elongate. Color 

 dark above; sides silvery, a dark lateral band; below this a pale 

 stripe; under which is a dark stripe which extends about to the vent; 

 fins plain; belly and pale stripe red in spring males. Head4f; depth 

 4^, D. 8 ; A. 8 ; scales 13-70-10 : teeth 2, 5-5, 2. L. 12 inches. Streams 



