218 FISHES OF WESTERN SOUTH AMERICA 
lateral line 40-42, in some areas 46-47; pectorals reaching ventrals; origin of ven- 
trals equidistant between tip of snout and base of the last third or fourth of the 
anal; caudal lobes more pointed than in H. helleri, a little longer than the head; 
ventrals reaching the anal in the smaller specimens. Humeral spot fainter, margin 
of anal darker than in H. helleri, numerous chromatophores between middle of anal 
and lateral line; middle caudal rays black; frontals entirely separated by the 
fontanel and ethmoid even in the largest. In other respects like H. hellert. 
These specimens, differing more or less from Steindachner’s figure of H. 
huambonicus, may represent a distinct species, although his area is embraced within 
the extremes of our range. 
243. HEMIBRYCON JELSKIL (Steindachner) 
Tetragonopterus jelskii Steindachner, 1875, Sitzb. Kix. Akad. Wiss. Wien, LX XII, 40, Monterico; 
Steindachner, 1882 (1883), Denksch. KIk. Akad. Wiss. Wien, XLVI, 25, Rio de Huambo, 
one, 115 mm. 
Hemibrycon jelskii Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 432; 
Higenmann, 1927, Mem. Mus. Comp. Zool., XLIII, iv, 412; 
Pearson, 1937a, Proc. Cal. Acad. Sci., (4), X XIII, 92. 
Eastern slopes of central Peru 
17640, 54, 30-40 mm., Rio Pusoc, upper Maranon, Pearson, 1922. 
A species not well characterized except in mathematical terms, and resembling 
H. dariensis. 
Genus 94: ACROBRYCON Ejigenmann and Pearson 
Tetragonopterus (in part) Cope, 1878, Proc. Amer. Phil. Soc., XVII, 44, Rio Urubamba. 
Hemaibrycon (in part) Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 482. 
Astyanax Fowler, 1906, Proc. Acad. Nat. Sci. Phila., LVIII, 337. 
Acrobrycon Eigenmann and Pearson, 1924, Ind. Univ. Studies, no. 64, 44. 
Type: Tetragonopterus ipanquianus Cope 
Atlantic slopes of the Andes of Peru and Bolivia 
Intimately allied to Hemibrycon, from which it differs in that the male bears a 
large caudal pouch; scales extend much farther back on the middle of the caudal 
than above or below, and along the ventral side only half as far as midway; the 
scales of the lower portion of the caudal not attached to rays, but to skin which is 
pouched away from the rays. 
244. ACROBRYCON IPANQUIANUS (Cope) 
Tetragonoplerus tpanquianus Cope, 1878, Proc. Amer. Phil. Soc., XVII, 44, collected by Orton on 
the Urubamba; 
Cope, 1878, Proe. Amer. Phil. Soc., XVII, 691, the Maranon; 
Rigenmann and Higenmann, 1891, Proce. U.S. Nat. Mus., XIV, 53. 
Astyanax tpanquianus Fowler, 1907, Proc. Acad. Nat. Sci. Phila., LVIII, 337, fig. 25. 
