Jordan and Evermann. — Fishes of North America. 3143 
iuterorbital space broad and flat; eye large; its longitudinal diameter 
contained 2 times in interorbital space; snout sharp, slightly turned u]) 
at end; month large, oblique; lower jaw included; lips thin; maxillarj'- 
not quite extending to orbit ; gill-rakers 6+6, on first arch, close together, 
slender, the longest i diameter of orbit. Teeth 4-1, strong, hooked, grind- 
ing surface oblique, narrow, grooved, a notch just below the hook; alimen- 
tary canal almost twice the length of body ; peritoneum dusky. Scales not 
crowded anteriorly, evenly distributed over body; lateral line shaped like 
the contour of body, except above pectoral fin, where it is sharply 
decurved; dorsal inserted directly above A^eutral, first ray highest, nearly 
3 times height of last; when depressed, the fin is falcate; when elevated, 
its edge is concave; anal similar in shape; caudal deeply forked, the tips 
sharp; ventrals pointed, not reaching vent; pectoral slightly rounded. 
Color silvery; darker above, especially on median dorsal area, where a 
more or less dusky band extends the length of the body; rays of dorsal 
fin and tips of caudal dusky; lower fins white. 
Exact measurements of the only specimen obtained are here given : 
Length of body in millimeters 92 ; depth of body, ex^iressed in hundredths 
of length, 23; depth of caudal peduncle 114; length of head 284; width of 
interorbital space 114; length of snout 8; diameter of orbit 6; distance 
from snout to dorsal fin 52; height of longest dorsal rays 20; distance 
from snout to anal fin 73 ; height of longest anal rays 17 ; distance from 
anal to caudal fin 21 ; length of caudal fin 25 ; length of pectoral fin 18 ; 
distance from snout to ventral fin 53; length of ventral fin 16. (Jordan 
&. Snyder.) 
Only the type known (Xo. 6151, L. S. Jr. Univ. Mns.) collected by J. 
O. Snyder in Laguna de Chapala, near Ocotlan, Jalisco, Mexico. 
Xystrqsus popoche, Jordan <fc Snyder, Bull. IT. S. Fi.sb Com. 1809 (1900), 123, Laguna de 
Chapala, Mexico. 
123 (b). FALCULA, Jordan & Snyder. 
Falcula, Jordan & Snyder, Bull. U. S. Fish Com. 1899 (1900), 124 {chapalce). 
Body long, compressed; caudal slender; mouth large, lips thin, pro- 
maxillaries protractile ; no barbel; teeth in 1 row, 4-4, hooked, grinding 
surface grooved; gill-rakers few, short, far apart; alimentary canal short; 
peritoneum silvery; lateral line complete; scales rather small, about 50 in 
lateral series. Fins high, falcate; dorsal inserted dir(‘ctly over ventrals; 
anal basis short; first simple rays of dorsal and anal rudimentary and 
closely adnate to first branched ray; caudal long, deeply notched. 
The genus Falcula is related to Notropls, from which it difters in its 
small scales and in its very high falcate fins, (falx, scythe.) 
498 (li). FAL( I L.V < H.U’Ab.K, Jonl.-ui A Snyder. 
Head 4; depth 44; eye 3j in head; snout 3J; iuterorbital space 83; 
depth of caudal peduncle 94; height of dorsal 4 in length ; anal 5; length 
of pectoral 4^; A'eutral 5.^; caudal 31; D. 8; A. 8; 1*. 17; scales 50, 
19 between dorsal and occiput, 16 between dorsal and ventral fins. 
