124 FISHES OF WESTERN SOUTH AMERICA 
Genus 82: MEGALODORAS Ejigenmann 
Megalodoras Eigenmann, 1925, Trans. Amer. Phil. Soc., XXII, 306. 
Type: Megalodoras irwint Eigenmann 
Rio Maranon, Middle Amazon and British Guiana 
Mouth wide, head depressed; adipose longer than anal and extended forward 
as a keel; air-bladder two-chambered with both parts fringed with numerous di- 
verticula, much depressed; dorsal spine with posterior serrae small or obsolete; 
lateral scutes few, less than 23. 
74. MEGALODORAS IRWINI Eigenmann 
Megalodoras irwint Eigenmann, 1925, Trans. Amer. Phil. Soe., XXIT, 307, pl. 1, fig. 4; pl. 11, fig. 3; pl. 
vi, figs. 1-4; pl. xxv, fig. 2; text fig. 11, f. 
15427, 5, 90-315 mm., type and paratypes, Iquitos, Allen, 1920 and Morris, 1922. 
Iquitos to Santarem 
Genus 33: CENTRODORAS Eigenmann 
Centrodoras Figenmann, 1925, Trans. Amer. Phil. Soc., XXII, 309. 
Type: Doras brachiatus Cope 
Amazons 
Most characters those of Megalodoras; much more numerous lateral scutes, 
each side with 38-40; dorsal spine with antrorse hooks on the anterior margin, the 
hooks behind varying from retrorse to straight; air bladder cardiform with numer- 
ous tufts of diverticula; a second bladder also with tufted diverticula. Three 
scutes in contact with the dorsal plate, about three rapidly decreasing in size, the 
remainder narrow. 
75. CENTRODORAS BRACHIATUS (Cope) 
Doras brachiatus Cope, 1871, Proc. Acad. Nat. Sci. Phila., 270; 
Eigenmann and Higenmann, 1890, Occ. Papers Cal. Acad. Sei., I, 234; 
Kigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 393. 
Centrodoras brachiatus Eigenmann, 1925, Trans. Amer. Phil. Soc., X XII, 310, text fig. 16; 
Fowler, 1939 (1940), Proc. Acad. Nat. Sci. Phila., XCI, 225, one, 163 mm., Contamana. 
The Amazons 
The origin of Cope’s specimens is only known to have been the Robert Per- 
kins collection made at various points between the Huallaga and the Rio Negro. 
It may belong to the area under present consideration; otherwise it is Brazilian. 
