254 



U. S. p. R. R. EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



NOCOMIS, Girard 



Gen. Char. — Body short, stoutieh and compreeeed, covered with large scales. The ventrals are inserted opposite the anterior 

 margin of the doreal, perhaps somewhat anterior to it. The caudal is furcated. The head is large, rounded upon the snout, 

 which is declivous. The mouth is large and terminal, the lower jaw being slightly overlapped by the upper. A barbel upon the 

 posterior extremity of the maxillary. Eyes moderate sized. Isthmus rather wide. The pharyngeals are stouiisli, somewhat 

 expanded upon their convexity; expansion tapering off towards the tip of the upper limb, which is gently curved inwards. The 

 inferior limb is scarcely longer than the upper, looks more slender, is flattened upon its extremity, which is turned outwards, 

 causing a convexity inwardly. The teeth are of the voratorial kind of the hooked type, without grinding surface. They are 

 Bub-cylindrical, acerated and hooked, disposed upon a double series of one and four, in the following manner: 1 | 4 — 4 | 1. 



Sys.—Nocomui, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 190. 



This genus is allied to Semotilus by its pharyngeal teeth, differing chiefly from it by its 

 mouth, which is not so deeply cleft, and by the presence of maxillar barbels, which are 

 wanting in Semotilus. 



A second species of this genus, N. belUcus, inhabits the Black Warrior river, Alabama, and 

 is mentioned in the "Proceedings of the Academy of Natural Sciences of Philadelphia, vol. 

 VIII, 1856, 213." 



NOCOMIS NEBRASCENSIS, Grd. 



Spec. Char. — Head contained four times and a half in the total length. Posterior extremity of maxillary even with a vertical 

 line drawn behiud the nostrils. Eye sub-circular; its diameter entering five times in the length of the side of the head. Body 

 etoutish and compressed, covered with large scales. Anterior margin of dorsal fin nearer the insertion of the caudal than the 

 extremity of the snout. Dorsal and anal fins deeper than long. Caudal fin constituting the fifth of the length. Tip of ventrals 

 overlapping the vent, although not reachiog the anal fin. Reddish brown above, golden yellow beneath. 



Syn. — Noccmk ruhrascensis, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, ]856, 190. 



The anal fin is inserted jjosteriorly to the dorsal, both being narrower than high or deep. 

 The ventrals are rather small ; the pectorals being moderate sized. 



D 1, 8 + 1 ; A 1, 7 + 1; C 9, 1, 9, 8, 1, 8 ; VB; P IT. 



The scales are nearly as deep as long, anteriorly sub-truncated, posteriorly rounded, with 

 radiating grooves upon their posterior section only. The lateral line is nearly median, being 

 but slightly deflexed upon the thoracic region. 



It is a fish about four inches in total length, of a uniform reddish brown hue above, and 

 golden yellow beneath ; a blackish streak is observed along the middle of the flanks terminating 

 into a black spot at the base of the caudal fin. 



List of specimens. 



