60 



UNITED STATES AND MEXICAN BOUNDARY. 



LUXILUS LEPTOSOMUS, G r d . 



Plate XIX, Figs. 9—12. 



Spec. Char.— Outline regularly sub-fusiform ; the depth forming a little more than the fifth of the entire length. The head 

 enters five times and a half in the latter dimension. The anal fin is a great deal larger than the dorsal. 



Syn. — Luxilus leptosomus, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 203. 



The scales are larger than in any other species of the same genus ; they are ahout as deep as 

 long, anteriorly uneven, posteriorly rounded, with radiating furrows upon their posterior section 



alone. 



D 9 ; A 2, 13 ; C 5, 1, 9, 8, 1, 5 ; Y 9 ; P 15. 



Color greyish brown above ; light reddish beneath ; sides silvery. Edge of the furcated por- 

 tion of the caudal, blackish grey. 



Plate XIX, fig. 9, represents Luxilus leptosomus^ size of life ; fig. 10 is a scale from the 

 dorsal region ; fig. 11, a scale from the lateral line ; and, fig. 12, a scale from the abdominal 



region. 



(The scales are represented in a reversed position.) 



List of specimens . 



Catal. 

 No. 



No. of 

 spec. 



Age. 



Locality. 



When 



collected. 



Whence obtained. 



Nature of 

 specimen. 



Collected by — 



61 



1 Adult. 



Dry creek, near Victoria, Tex. 



1854 



Maj. Emory 



Alcoholic. 



D. C B. Kennerly 









TIAl 



*OGA, ( 



jir ar d. 







Gen. Char. — Head small, sub-conical, depressed. Mouth obliquely terminal, of moderate size, and without barbels of any 

 kind. Upper jaw slightly longer than the lower. Eye of medium size. Isthmus very wide. Body slender, sub-fusiform, 

 compressed. Fins are well developed; dorsal and anal narrow and high; caudal furcated. The insertion of the ventrals 

 takes place in advance the anterior margin of the dorsal. The scales are small, deeper than long, with radiating furrows all 

 around ; the lateral line is median. The pharyngeals are similar to those in Gobio. The teeth are likewise of the same 

 character : slender, sub-cylindrical upon their base, compressed upwards, of the raptatorial kind, of the hooked type, without 

 grinding surface, and disposed upon a double row of one and three, thus : 1 J 3 — 3 | 1. 



Syn.— Tiaroga, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 204. 



This genus bears some analogy to the Gudgeons (Gobio), differing from them by the absence 

 of barbels, either maxillar or buccal, and hv a Iars nrmrnnpnf. snnnt 



TIAROGA COBITIS, Grd. 

 Plate XXVIII, Figs. 11—14. 





Spec. Char.— Two inches and a half in total length, the head forming about the fifth part of it. Eyes approximating the 

 toper surface of the head, which is rounded. 



Stn.— Tiaroga eobitis, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 204. 



The scales are deeper than long, elliptical, with wide radiating pericentrical furrows. 



+ i;ai,h 



15. 



The upper regions are brownish, with small blackish spots ; the inferior regions are unicolor 

 of a yellowish tint. A black spot upon the base of the caudal fin. 



