CENTROPOMUS. 45 
1. CENTROPOMUS, Lacep., 1802. 
Centropomus, Bouleng. Cat. Fish. i. p. 366 (1895); Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 
1896, p. 1117. 
Body compressed ; scales small or of moderate size, finely ctenoid. Lateral line nearly straight, continued to 
the end of the caudal fin. Mouth rather large, protractile; maxillary exposed ; lower jaw projecting ; 
bands of villiform teeth with obtuse crowns in jaws and on vomer and palatines. Praorbital and supra- 
clavicle serrated. Praoperculum with a ridge parallel to its free edge, bearing 1 or 2 spines at the angle ; 
edge of preeoperculum serrated, with enlarged serra or spines at the angle ; suboperculum produced into 
a long flap. Two dorsals, with VIII, 1 9-11 rays; the first spine very small, the second short, the third 
or fourth the longest; anal short, with III 6-7 rays; caudal forked; pectoral asymmetrical, obtusely 
pointed; ventrals behind base of pectorals, with I 5 rays; a scaly process at the base of the spine of each 
ventral fin. 
Hab. Coasts and rivers of Tropical America. 
I am glad to have the opportunity of attempting a revision of this interesting and 
difficult genus, and, after examination of all the specimens in the British Museum 
collection, I have arrived at the conclusion that none of the species occur on both the 
Pacific and Atlantic Coasts. 
Although marine, nearly all the species are known to ascend rivers for considerable 
distances, so that they must be included in the fresh-water fauna. 
Synopsis of the Species. 
I. Anal with 7 branched rays; opercular flap not extending to the vertical from origin of dorsal ; 
second and third anal spines of equal length, or the second slightly the shorter. 
66-72 scales in a longitudinal series, 84 between middle of second dorsal and 
lateralline . 2... we ee ee ee eee ee ww we OL petinatus. 
56-65 scales in a longitudinal series, 64 to 74 between middle of second dorsal 
and lateral line . «© 2. 1 ee ee eee eee ee wR. medius. 
II. Anal with 6 (exceptionally 7) branched rays. 
A. Opercular flap extending to the vertical from origin of dorsal ; 75-88 scales 
in a longitudinal series ; second anal spine a little longer than the third. 3. parallelus. 
B. Opercular flap not extending to the vertical from origin of dorsal; 65-80 scales in a 
eae series. 
. Third dorsal spine usually the longest, about 4 the length of head; 65-75 
scales in a longitudinal series, 7} to 83 between middle of second dorsal 
and lateral line. 
Second anal spine usually slightly longer than the third, }—} the length 
of the fish (4 in specimens of 295-330 mm.) ; vent at more than 4 
of the distance from base of ventral spine to origin of anal. . . . 4. undectmalis. 
Second anal spine not longer than the third, nearly + the length of the 
fish (in specimens of 320-345 mm.); vent at less than 2 of the 
distance from base of ventral spine to origin of anal. . . . . 5. viridis. 
2. Third or fourth dorsal spine the longest, 2? the length of head ; 73-80 
scales in a longitudinal series, 9 or 10 between middle of second dorsal 
and lateral line; second anal spine not longer than the third. . . . 6. nigrescens. 
