ANNOTATED LIST OF THE SPECIES all 
to the pectoral spine; mental barbel about reaching the postmental, the postmental 
not to the pectoral; coracoid process granular; dorsal spine reaching from snout to 
end of opercular membrane, with fine granules on anterior face, and fewer and a 
little larger spines behind; the pectoral spines reaching to origin or middle of the 
ventral, with serrae considerably longer than those of the dorsal, the anterior an- 
trorse, the posterior retrorse; gill opening not extending below the dorsal margin of 
the pectoral spine; ventrals rounded, not extending to anal; anterior anal rays 
longer, but not faleate; caudal oblique, adipose small but well developed. 
Greenish above, light below, shading from the middle of the back to the lateral 
line, free from chromatophores; upper part of sides with vertical series of pores in 
pigment-free areas; base of caudal rays pigmented. 
Differing from its near ally 7. galeatus in the granular coracoid process and 
head wide but narrower than its length. 
Genus 29: AUCHENIPTERUS Cuvier and Valenciennes 
Auchenipterus Cuvier and Valenciennes, 1840, Hist. Nat. Poiss., XV, 207, nuchalis; 
Eigenmann and Eigenmann, 1890, Oce. Papers Cal. Acad. Sci., I, 294; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, IIT, 397; 
Eigenmann, 1912, Mem. Carnegie Mus., V, 202. 
Evanemus Miller and Troschel, 1849, Horae Ichth., III, 11, colymbetes. 
Type: Hypophthalmus nuchalis Spix 
The Guianas and the Amazon 
Of the six barbels the two pairs of mentals are disposed in a straight, trans- 
verse line near the symphysis; pectorals and ventrals rather long, the former with 
rays I, 11; the latter 12-15 and posterior to the dorsal; the adipose short, the anal 
long; the zigzag lateral line with short branches; humeral process usually concealed. 
70. AUCHENIPTERUS NUCHALIS (Spix) 
Hypophthalmus nuchalis Spix, 1829, Sel. Gen. et Spec. Pisce. Bras., 17, pl. xvii. 
Auchenipterus nuchalis Cuvier and Valenciennes, 1840, Hist. Nat. Poiss., XV, 207; 
Eigenmann and Eigenmann, 1888, Proc. Cal. Acad. Sci., (2), I, 151; 
Eigenmann and Eigenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 295; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, I, 397; 
Fowler, 1939 (1940), Proc. Acad. Nat. Sci. Phila., XCI, 231, Contamana. 
Euanemus nuchalis Giinther, 1864, Cat. Fish. Brit. Mus., V, 193; 
Cope, 1878, Proc. Amer. Phil. Soc., XVII, 676, Peruvian Amazon. 
The Amazons to Surinam 
Mapara, Fowler, native name 
15661, 2, 162 and 203 mm., Rio Morona, Allen, October, 1920. 
15662, 7, 147-178 mm., Iquitos, Allen, September, 1920. 
15776, 1, 205 mm., Gosulimacocha, Rio Morona, Allen, October, 1920. 
15777, 2, 165 and 2538 mm., Rio Huallaga, Yurimaguas, Allen, November, 1920. 
15778, 3, 197-233 mm., Manaos, Allen, December, 1920. 
15978, 1, 163 mm., Iquitos, Morris, 1922. 
