No. 4 



BY CHARLES GIRAftD, M. D. 



1. BRYTTUS HUMILIS, Grd. 

 GEN. REP. 21. PLATE VII, FIGS. 924. 



SPEC. CHAR. Body sub-ellipitical. Nape convex, and snout sub-conical. Posterior extremity of maxillary extending beyond 

 the anterior rim of the orbit. Insertion of the ventral situated posteriorly to the base of pectorals, and a little in advance of 

 the origin of the dorsal, their tips overlapping the vent. Scales large. Keddish brown or dusky, maculated. Fins uriicolor ; 

 dorsals sometimes blotched. 



429. Cottonwood creek, Utah. Mr. Kreuzfeld. 



2. AMBLODON GRUNNIENS, R a fi n .Buffalo Perch, Grunting Perch, &c. 



GEN. REP. 96. PLATE XXIII. 



SPKC. CHAR. Profile of head depressed on the nape. Snout thick, blunt, and short. Posterior extremity of maxillary 

 extending to a vertical line intersecting the anterior rim of the pupil. Extremities of pectorals almost even with the tips of 

 ventrals, or else projecting slightly beyond them. First anal spine diminutive ; second one stout and well developed. Caudal 

 fin posteriorly convex. Color bluish-grey, lighter beneath than above. Fins greyish-olive ; anal maculated. 



483. St. Louis, Missouri. Dr. Geo. Engelmann. 



3. PTYCHOSTOMUS HAYDENI, Grd. 

 GEN. REP. 220. PLATE XLIX, FIGS. 14. 



SPEC. CHAR. Body sub-fusiform. Head contained five times and a half in the total length. Eye sub-circular, moderate 

 sized; its diameter entering five times in the length of the side of the head Dorsal fin higher than long; its anterior margin 

 being much nearer the tip of the snout than the insertion of the caudal The latter is furcated. Insertion of ventral fins 

 situated opposite the middle of the dorsal. Anal much deeper than broad. Pectoral moderate sized. Scales longer than deep, 

 furrowed upon their anterior and posterior sections. 



172. Yellowstone river. Dr. F. V. Hayden. 



4. ACOMUS GENEROSUS, Grd. 

 GEN. REP. 222. 



SPEC. CHAR. Head constituting the fifth of the total length ; mouth moderate sized ; lips rather small, covered with uniform 

 granules. Eye small, sub-circular ; its diameter entering five times in the length of the side of the head. Anterior margin of 

 dorsal fin equidistant between the extremity of the snout and the insertion of the caudal. Extremities of ventrals not reaching 

 the vent ; their origin taking place under the posterior third of the dorsal. Olivaceous above, blotched with blackish ; yellowish 

 olive beneath. Fins unicolor. 



256. Cottonwood creek, Utah. Mr. Kreuzfeld. 



