THE AMERICAN TETRAGONOPTERINAE. 275 



a distinct median series of scales, about 17 scales in front of the ventrals; post- 

 ventral area narrowly rounded. Predorsal area narrow, bluntly keeled, without 

 a distinct median series of scales, about 13 scales in front of the dorsal. 



Interorbital convex, smooth. Occipital process about one fourth of the 

 length from its base to the dorsal, bordered by four or five scales along each 

 side, usutUly a few small scales about its tip. Frontal fontanel narrow, triangu- 

 lar, not very much shorter than the parietal without its groove. Mouth small; 

 snout pointed; second suborbital narrower than the eye, leaving a naked border 

 aroimd its entire margin. Maxillary not extending beyond origin of the eye; 

 maxillary-premaxillary border angulated, equal to half the length of the head 

 without the opercle, lower jaw short, comparatively weak. Four or five teeth 

 in the outer row of the premaxillary, five in the inner, the lateral one minute; 

 one tooth on the maxillary ; five or six graduated teeth on the mandible in front 

 and sometimes a few minute ones on the side. 



Gill-rakers 7 -|- 12. 



Origin of dorsal about equidistant from caudal and snout, its height 4—4.5 

 in the length; adipose well developed; caudal lobes 4-4.3 in the length. Origin 

 of anal equidistant from caudal and origin or middle of pectoral. Depth of 

 caudal peduncle 1.25-1.33 in its length. Ventrals small 1.5-1.66 in the length 

 of the head, not reaching the anal. Pectorals reaching to or nearly to the 

 ventrals, equal to head without snout or a little longer. 



Scales very regularly imbricate, the rows not deflected toward the anal 

 by interpolated rows; caudal naked; anal with a very narrow sheath, of one 

 row of scales in front; a well-developed axillary scale. Lateral line but very 

 little decurved. 



A vertical humeral spot widest and most intense over the lateral line. A 

 silvery lateral band, expanded at the end of the caudal peduncle; no spots or 

 bands on the fins. 



31. AsTYANAX CORDOVAE (Giinther). 



Plate 44, fig. 3. 



Tetragonopterus cordovae Gunther, Ann. mag. nat. hist., 1880, ser. 5, 6, p. 12 (Rio de Cordova); Eigen- 

 MANN & EiGENMANN, Proc. U. S. N. M., 1891, 14, p. 53; Ulbey, Ann. N. Y. acad. sci., 1895, 8, p. 

 278; Peeugia, Ann. Mus. civ. storia, nat. Genova, 1891, ser. 2a, 10, p. 43 (Jubibiri). 



Asti/miax cordovae Evermann & Kendall, Proc. U. S. N. M., 1906, 31, p. 82 (Rio Primero, Cordova). 



Habitat. — Western Argentina. 



One specimen. 11093 I. 66 mm. to base of caudal. Rio Primero. Titcomb. 



