Jordan and Evcnnann. Fishes of North America. 3143 



interorbital space broad and flat; eye large; its longitudinal diameter 

 contained 2 times in interorbital space; snout sharp, slightly turned up 

 at end; mouth large, oblique; lower jaw included; lips thin; maxillary 

 not quite extending to orbit ; gill-rakers 6+6, on first arch, close together, 

 slender, the longest \ diameterof orbit. Teeth 4-4, 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 

 decarved; dorsal inserted directly above ventral, 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; A'ontrals pointed, not reaching vent; pectoral slightly rounded. 

 Color silvery; darker above, especially on median dorsal area, where a> 

 more or less dusky baud 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, expressed in hundredths 

 of length, 23; depth of caudal peduncle 1U; length of head 28; width of 

 interorbital space 11|; 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 (No. 6151, L. S. Jr. Univ. Mus.) collected by J. 

 O. Snyder in. Laguna de Chapala, near Ocotlan, Jalisco, Mexico. 



Xystrosus popoche, JORDAN & SNYDER, Bull. TJ. S. Fish Com. 1899 (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, pre- 

 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, fal'cate; dorsal inserted directly 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 Notropis, from which it differs in its 

 small scales and in its very high falcate fins, (falx, scythe.) 



498 (b). FALCULA CHAPAL.E, Jordan & Snyder. 



Head 4; depth 4|; eye 3 in head; snout 3|; interorbital space 3; 

 depth of caudal peduncle 94-; height of dorsal 4 in length; anal 5; length 

 of pectoral 4| ; ventral 5|; caudal 3J; D. 8; A. 8; P. 17; scales 50, 

 19 between dorsal and occiput, 16 between dorsal and ventral fins. 



