31 - 1:2 
Bulletin //, United States A^ational Museum. 
oblique, lower jaw included; maxillary not ijuite 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 tin longest, last ray much shorter; when the tin is elevated, the 
posterior margin is straight, when depressed, it is somewhat falcate; anal 
tin similar in shape; pectoral pointed; tips of A'entrals reaching anal; 
caudal deeply forked, the lobes ])ointed. Color silvery, a dark lateral 
band, the width of a scale, extending from tip of snout through eye to 
base of caudal, Avhere it ends in an elongate, black spot; body above 
lateral baud stippled with black, the dots grouped clo.sely together on top 
of head, and in a narrow dorsal band extending from occiput to imsertion 
of dorsal, in a sharjily 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. 
Xotro})is rasconis is closely related to X. mgrotwniatua, from which it 
ditfers 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 Sc Snyder.) 
Known only from the Rio Verde near Rascon, San Luis Potosi, Mexico, 
Avhere the type (Xo. 6153, L. S. Jr. Uuiv. Mus.) Avas collected by J. O. 
Snyder. 
(Named for Rascon, near which place the type Avas obtained.) 
Xotropis rasconis, .JORDAN i Snyder, Bull. V. S. Fish Com. 189'J (1900) 121, Rio A/erde, near 
Rascon, Mexico. 
Page 302. P>efore Ericymha, Cope, insert: 
123 (a|. XYSTROSUS, Jordan A: Snyder. 
Xygtrosus, Jordan A: Snyder, Bull. U. S. Fish Com. 1899 (1900), 123 (jwpoche). 
Body long, compressed; iuterorbital space low and fiat ; mouth terminal, 
obli(iue; jaws subequal; premaxillaries protractile ; no barbel; no])seudo- 
branchiic; gill-rakers 6-f-6, long, slender, crowded on arch; teeth 4-4, 
hooked, grinding surface oblique, grooA'cd; alimentary canal about twice 
as lougasbody; peritoneum dusky; lateral line complete, decurved above 
pectoral; scales 61, evenly distributed over body; fins falcate; dorsal 
inserted directly above insertion of ventral; caudal deei)ly forked; anal 
basis short. Allied to Xotropis; diftering in the long gill-raker.s, the small 
scales, and the absence of pseudobranchia-. ivSrpov, (gill-)raker. 
49.H (a). XYSTK0>«rS POIMK'HK, .Jordan Snyder. 
He.ad 34; depth 44; eye 4J in head; snout 3J; dei)th of caudal 
peduncle 24; height of dorsal 5 in length; anal 6; length of pectoral 6; 
A'cntral 6;f ; caudal 4; D. 8; A. 7 ; P. 16; scales 61, 24 between dorsal and 
occijjut, 16 between dorsal and lateral line. Bo<ly long and slender; 
caudal peduncle deep, compressed; head long, itsuj>per contour straight; 
