3142 Bulletin 4.7, United States National Museum. 



oblique, lower jaw included; maxillary not quite reaching vertical from 

 anterior margin of orbit. Teeth 4-4, frail and easily detached from the 

 arch, slightly hooked, no evident grinding surface; gill-rakers short and 

 blunt, reduced to slight elevations on lower part of first arch. First ray 

 of dorsal fin longest, last ray much shorter; when the fin is elevated, the 

 posterior margin is straight, when depressed, it is somewhat falcate; anal 

 fin similar in shape; pectoral pointed; tips of ventrals reaching anal; 

 caudal deeply forked, the lobes pointed. Color silvery, a dark lateral 

 band, the width of a scale, extending from tip of snout through eye to 

 base of caudal, where it ends in an elongate, black spot; body above 

 lateral band stippled with black, the dots grouped closely together on top 

 of head, and in a narrow dorsal band extending from occiput to insertion 

 of dorsal, in a sharply defined black line along base of dorsal fin, and also 

 on the edges of the dorsal scales; body below dark band immaculate, 

 except a dusky line along base of anal fin ; all the fin rays dusky, especially 

 the partly developed caudal rays, which are noticeably darker than the 

 others. 



Notropis rasconis is closely related to JV. nigrotceniatus, from which it 

 differs in having a more compressed body, a longer snout, larger eye, 

 longer and more pointed fins, and in having the color-band narrower on 

 the body and more marked on the snout. (Jordan & Snyder.) 



Known only from the Rio Verde near Rascon, San Luis Potosi, Mexico, 

 where the type (No. 6153, L. S. Jr. Univ. Mus.) was collected by J. O. 

 Snyder. 



(Named for Rascon, near which place the type was obtained.) 



Notropis rasconis, JORDAN & SNYDEK, Bull. U. S. Fish Com. 1899 (1900). 121, Rio Verde, near 

 Rascon, Mexico. 



Page 302. Before Ericyniba, Cope, insert: 



123 (a). XYSTROSUS, Jordan & Snyder. 

 Xystrosus, JORDAN SXYDER, Bull. IT. S. Fish Com. 1899 (1900), 123 (popoche). 



Body long, compressed; interorbital space low and flat ; mouth terminal, 

 oblique; jawssubequal; premaxillaries protractile; no barbel: no pseudo- 

 branchia3; gill-rakers 6+6, long, slender, crowded on arch; teeth 4-4, 

 hooked, grinding surface oblique, grooved; alimentary canal about twice 

 as longasbody ; peritoneum dusky; lateral line complete, decurved above 

 pectoral; scales 61, evenly distributed over body; fins falcate; dorsal 

 inserted directly above insertion of ventral; caudal deeply forked; anal 

 basis short. Allied to Notropis; differing in the long gill-rakers, the small 

 scales, and the absence of pseudobranchire. cutirpov, (gill-)raker. 



498 (a). XYSTROSUS POPOCHE, Jordan & Snycler. 



Head 3; depth 4-J-; eye 4f in head; snout 3f; depth of caudal 

 peduncle 2; height of dorsal 5 in length; anal 6; length of pectoral 6; 

 ventral 6i; caudal 4; D. 8; A. 7; P. 16; scales 61, 24 between dorsal and 

 occiput, 16 between dorsal and lateral line. Body long and slender; 

 caudal peduncle deep, compressed; head long, its upper contour straight; 



