220 



U. S. P. R K. EXP. AND SUEVEYS ZOOLOGY GENERAL REPORT. 



D 13 ; A 10 ; C 4, 1, 8, 8, 1, 3 ; V 9 ; P 15. 



The scales are sub-elliptical in general shape, presenting no grooves upon their lateral 

 sections, but few upon the anterior section, and numerous posteriorly upon that section of the 

 scale that is exposed. 



The color is yellowish brown, lighter beneath than above, where a dusky hue sometimes 

 prevails. The sides and inferior surface of the head are likewise rather yellowish olive. 



References to the figures. Plate XLVIII, fig. 5, represents Moxostoma daviformis, size of 

 life. Fig. 6, an outline from above. Fig. 7, a section of the body, taken across the line of 

 greatest depth. Fig. 8, a scale from the dorsal, region. Fig. 9, a scale from the abdominal 

 region. 



List of specimens. 



PTYCHOSTOMUS, Agass. 



GEN. CHAR. Head short and stout. Mouth protractile and directed downwards. Transverse folds or ridges upon the lips. 

 Inferior lip but slightly lobed. Body sub-fusiform, elongated, covered with well developed scales, as large anteriorly as 

 posteriorly. 



STN. Ptychostomus, AGASS. in Arner. Journ. of Sc. 2d series, XIX, 1855, 88. GRD. in Proc. Acad. Nat. Sc. Philad. 

 VIII, 1856, 172. 



Resembles Catostomus in its general appearance. The height of the dorsal may be either 

 equal to its length or somewhat higher than long. The wing-like expansions of the pharyngeals 

 is anything but characteristic of this genus. The conspicuous lateral line will at once dis 

 tinguish it from Moxostoma. The mouth is much more protractile, and directed more down 

 wards than in the latter mentioned genus. 



PTYCHOSTOMUS HAYDENI, Grd. 

 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. 



SYN. Ptychostomus haydeni, GRD. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 172. 



The head is contained five times and a half in the total length. The body is sub-fusiform, 

 very regular in its outline. The eye is sub-circular and moderate in its development ; its 

 diameter being contained five times in the length of the side of the head. The opercle is 

 largely developed, whilst the sub-opercle is small, a character which is more or less generical. 

 The dorsal fin is somewhat higher than long ; its upper margin is sub-concave, its anterior 

 margin being nearer the tip of the snout than the base of the caudal. The caudal is furcated. 



