222 



U S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



scales are larger than in A. griseus, especially those on the anterior portion of the body. The 

 lateral line runs nearly straight along the middle of the flanks to the base of the caudal. 



The color of the dorsal region and sides of the body is olivaceous, obscurely dark blotched ; 

 the inferior regions being unicolor, yellowish olive. All the fins assume the latter tint. 



List of specimens. 



2. ACOMUS GKISEUS, Grd. 

 PLATE XLIX, FIGS. 59. 



SPEC. CHAR. Head constituting the fifth of the entire length. Mouth moderate sized. Granules of lower lip largest close 

 to the mouth. Eye small, sub-elliptical; its longitudinal diameter entering about seven times in the length of the side of the 

 head. Anterior margin of dorsal fin equi-distant between the extremity of the snout than the insertion of the caudal. 

 Extremities of ventrals not reaching the vent ; their origin taking place under the posterior third of the dorsal. Greyish brown 

 above ; whitish or yellowish beneath. 



SYN. Catostomus (Acomus] griseus, GRD. in Proc. Acad. Nat Sc. Philad. V T TI, 1856, 174. 



The body is slender, gracefully fusiform in its outline, the head forming the fifth of the 

 entire length. The longitudinal diameter of the eye is contained seven times in the length of 

 the side of the head in the adult, and five times in the young. The anterior margin of the 

 dorsal is equi-distant between the tip of the snout and the insertion of the caudal fin. The 

 ventrals are inserted opposite the posterior third of the dorsal. The anal is slender. 



D 13 ; A 10 ; C 6, 1, 8, 8, 1, 5 ; V 10 ; P 16. 



The scales are elliptical in their outline, exhibiting radiating furrows upon their entire 

 periphery. In the lateral line they assume various sizes and shapes. 



The color of the upper regions is greyish brown ; the inferior regions being whitish or 

 yellowish. The dorsal and caudal are olivaceous ; the anal and ventrals yellowish, whilst the 

 pectorals are greyish above and yellowish beneath. 



References to the figures. Plate XLIX, fig. 5, represents Acomus griseus, size of life. Fig. 6 

 is a scale from the dorsal region. Figs. 7 and 8, scales from the lateral line. Fig. 9, a scale 

 from the abdominal region. 



List of specimens. 



