388 FISHES OF WESTERN SOUTH AMERICA 
17752, 1, 132 mm., Rio Itaya, Allen, September, 1920. 
17753, 5, 126-215 mm., Contamana, Allen, August, 1920. 
17754, 3, 132-188 mm., Yarinacocha, Allen, August, 1920. 
17755, 1, 240 mm., Iquitos, Morris, 1922. 
17756, 1, 220 mm., Manaos, Allen, December, 1920. 
17757, 1, 180 mm., Maranon, Allen, October, 1920. 
In general form Chaetobranchus may be thought of as bearing the same rela- 
tionship to Cichla as does the croppie to the black basses of North America. 
Genus 201: ACARONIA Myers 
Acaropsis Steindachner, 1875, Sitzb. KIX. Akad. Wiss. Wien, LX-XT, 281; 
HKigenmann and Eigenmann, 1891, Proc. U.S. Nat. Mus., XIV, 68; 
Pellegrin, 1903 (1904), Mém. Soc. Zool. France, XVI, 144; 
FEigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 470; 
Kigenmann, 1912, Mem. Carnegie Mus., V, 485. 
Acaronia Myers, 1940, Stanford Ichth. Bull., I, 170. 
Type: Acaropsis nassa Heckel 
Amazonia, Orinoco drainage, Guianas 
The characters are largely those of 4quidens; the maxillary exposed to the 
extremity, the premaxillary highly protractile, mouth very large. 
496. ACARONIA NASSA (Heckel) 
Acara nassa Heckel, 1840, Ann. Wiener Mus., IT, 353, R. Guaporé; 
Miller and Troschel, in Schomburgk, 1848, Reisen, ITT, 624; 
Gunther, 1862, Cat. Fish. Brit. Mus., IV, 281. 
Acara (Acaropsis) nassa Steindachner, 1875, Sitzb. KIX. Akad. Wiss. Wien, LXXT, 81; 
Pellegrin, 1902, Bull. Mus. Hist. Nat., VITI, 182. 
Acaropsis nassa Kigenmann and Bray, 1894, Ann. N. Y. Acad. Sei., VII, 613; 
Pellegrin, 1903 (1904), Mém. Soc. Zool. France, XVI, 180; 
Regan, 1905, Ann. Mag. Nat. Hist., (7), XV, 345; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 470; 
Higenmann, 1912, Mem. Carnegie Mus., V, 485. 
Acaronia nassa Myers, 1940, Stanford Ichth. Bull., I, 170. 
Guianas, Orinoco, Amazons 
17794, 1, 240 mm., Manaos, Allen, December, 1920. 
This specimen, larger than any described from the Guianas, shows some de- 
partures from type. 
Scales deeply embedded; spines of dorsal and anal fins very stout, and arranged 
alternately with one another; the membranes of these fins and of the caudal much 
thickened, dark, and opaque; markings obscured, except for a caudal ocellus; poste- 
rior border of operculum with about twenty small, irregular, dark spots; vertical 
bands faintly perceptible; the lateral line decurved just before its interruption, and 
separated from the dorsal fin by 5-73 rows of scales. 
