ANNOTATED LIST OF THE SPECIES 189 
Type: Hypostomus aurantiacus Castelnau 
The Amazon valley 
Hemiancistrus and the present genus are scarcely separable except that the 
latter is marked by a greater or less continuity between the dorsal and adipose fins. 
175. PARANCISTRUS AURANTIACUS (Castelnau) 
Hypostomus aurantiacus Castelnau, 1855, Anim. Amér. Sud, Poiss., 48, pl. xxi, fig. 2, Rio Ucayali. 
Hypostomus nigricans Castelnau, 1855, Anim. Amér. Sud, Poiss., 44, pl. xxii, fig. 1. 
Hypostomus vicinus Castelnau, 1855, Anim. Amér. Sud, Poiss., 45, pl. xxi, fig. 1. 
Parancistrus aurantiacus Bleeker, 1863, Nederl. Tijdsch. Dierk., I, 79; 
Kigenmann and Eigenmann, 1889, Proce. Cal. Acad. Sei., (2), II, 44; 
figenmann and Eigenmann, 1890, Oce. Papers Cal. Acad. Sei., I, 424; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 409. 
Parancistrus nigricans EKigenmann and Kigenmann, 1889, Proc. Cal. Acad. Sci., (2), II, 44. 
Chaetostomus aurantiacus Ginther, 1864, Cat. Fish. Brit. Mus., V, 246. 
Chaetostomus nigricans Giinther, 1864, Cat. Fish. Brit. Mus., V, 246. 
Ancistrus aurantiacus Regan, 1904, Trans. Zool. Soc. London, XVII, 236. 
Peruvian Amazon 
Three specimens in British Museum. Imperfectly known through Castelnau’s 
figures and description. 
Genus 80: ACANTHICUS Spix 
Acanthicus Spix, 1829, Sel. Gen. et Spec. Pise. Bras., 2; 
Eigenmann and EKigenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 489; 
Regan, 1904, Trans. Zool. Soc. London, XVII, 261; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 412. 
Type: Acanthicus hystrix Spix 
The Amazon and tributaries 
Lacking adipose fin; postdorsal area with rather large plates; predorsal plates 
small and numerous, and isolated like those of the sides; entire margin of snout well- 
bristled. 
176. ACANTHICUS HYSTRIX Spix 
Acanthicus hystrix Spix, 1829, Sel. Gen. et Spec. Pisce. Bras., 3, pl. 1; 
Giinther, 1864, Cat. Fish. Brit. Mus., V, 253; 
Giinther, 1868, Proce. Zool. Soe. London, 233, Neberos; 
Eigenmann and Higenmann, 1889, Proc. Cal. Acad. Sci., (2), I, 46; 
Eigenmann and Higenmann, 1890, Oce. Papers Cal. Acad. Sei., I, 440; 
Regan, 1904, Trans. Zool. Soc. London, XVII, 262; 
EKigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 412. 
Amazon 
Three specimens known, collected by Bartlett, probably from Xeberos, possibly 
enroute down the Amazon. 
