318 FISHES OF WESTERN SOUTH AMERICA 
Similar to Higenmannia troscheli, differing in the characters mentioned in the 
description of the genus, and the tumid tail. 
Subfamily: APTERONOTINAE 
Sternarchinae Eigenmann, 1912, Mem. Carnegie Mus., V, 437. 
Gymnotids with caudal fin, tail short; orbital margin not free; a dorsal filament 
present; teeth in patches on one or both jaws. 
KEY TO THE GENERA OF THE SUBFAMILY APTERONOTINAE 
a. Snout produced, the eye behind the middle of the head; mouth small; teeth in both jaws 
b. Snout decurved; mouth minute............................STERNARCHORHYNCHUS 
bb. Snout straight 
¢G Mouth Warge. 2007722) ei nee eee eee  STURNARCHORHAMPEUS 
Cen. Mouth: minutes as 1M ibis 5. Se ereynns cients (extralimital) ORTHOSTERNARCHUS 
aa. Snout produced or not; mouth large; eye in anterior part of the head, or the rictus under 
the eye 
d. Lower jaw normal, included 
e. Teeth in both jaws normal 
f. Back scaled 
g. Mouth variable, its angle little if any in front of the eye. . APTERONOTUS 
gg. Mouth small, its angle under posterior nostril. ..STERNARCHELLA 
ff. Back naked, mouth small; scales above lateral line subcircular. .POROTERGUS 
ee, No teeth, or teeth confined to mandible; back naked; scales above the lateral line 
MU ChHhi ethers tiem el O12: see eee ysis lee ate e ean STERNARCHOGITON 
eee. Teeth strong, fixed, many on tumid, everted jaws; back naked; scales above the 
lateral Jine. much higher than long. .2..:2.../..:2.!..%: OEDEMOGNATHUS 
dd. Lower jaw heavy, projecting beyond the upper, both on the sides and in front; no teeth; 
ouvelke Aymilae stories hai inne suas be abn coae ma sbeurccsm ann oo! \ DONTOSTERNARCHUS 
Genus 176: STERNARCHORHYNCHUS Castelnau 
Sternarchorhynchus Castelnau, 1855, Anim. Amér. Sud, Poiss., 91, 95; 
Eigenmann and Eigenmann, 1891, Proc. U. S. Nat. Mus., XIV, 62; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, HI, 449; 
Eigenmann, 1912, Mem. Carnegie Mus., Vi, 4375 
Ellis, 19183, Mem. Carnegie Mus., VI, 140. 
Rhamphosternarchus Ginther, 1870, Cat. Fish. Brit. Mus., VI, 140. 
Type: Sternarchorhynchus miilleri Castelnau = 
Sternarchus oxyrhynchus Miller and Troschel 
Guianas to Peruvian Amazon 
With caudal fin; gape very small; patches of teeth on both jaws; head medium, 
conical; snout long, tubular, and somewhat decurved; no free orbital margin; fon- 
tanels present; caudal fin small, terminal, fan-shaped, slightly scaled at base; body 
compressed and slightly elongate, becoming very slender in caudal region; scales 
eycloid; lateral line complete; anal long, widest in the middle, narrowing toward 
both extremities. 
442. STERNARCHORHYNCHUS OXYRHYNCHUS (Miiller and Troschel) 
Sternarchus oxyrhynchus Miller and Troschel, 1848, in Schomburgk, Reisen, IIT, 640; 
Miiller and Troschel, 1849, Horae Ichth., III, 16, pl. ii, figs. 1 and 2; 
Kkaup, 1856, Cat. Apod., 127; 
