48 ACANTHOPTERYGII. 
spine the longest, 3-3 the length of head. Anal III 7; second and third spines of equal length or the 
second slightly the shorter, 1—2 the length of the fish. Pectoral } or a little more than 4 the length of 
head. Ventrals extending to or beyond the vent, which is nearly equidistant from base of inner ventral 
ray and origin of anal. Caudal peduncle 14-1% as long as deep. Silvery, back darker; lateral line 
black ; spinous dorsal and membrane between second and third anal spines blackish ; ventrals dusky at 
the tips. 
Hab. Pacific Coasts of Tropical America, entering rivers: 
Mexico, Guaymas ‘4, Mazatlan §, San Juan Lagoon 5; Guatemala, Chiapam !?7 
(Salvin); Panama ®. 
Here described from seven specimens, 200-360 mm. in total length, from Chiapam 
and Panama. 
C. medius is the Pacific Coast representative of C. pectinatus, from which it scarcely 
deserves to be specifically separated. The scales are less numerous and less crowded 
anteriorly above the lateral line, the paired ridges on the head are weaker and further 
apart, and the fin-spines usually more slender than in C. pectinatus. ‘The black 
lateral line also appears to be a characteristic feature of the Pacific Coast form. 
3. Centropomus parallelus. 
Centropomus undecimalis (part.), Giinth. Cat. Fish. i. p. 79 (1859) *. 
Centropomus parallelus, Poey, Mem. Cuba, ii. p. 120 (1860) *, and Repert. ii. p. 280 (1868) °; 
Giinth. Trans. Zool. Soc. vi. 1868, p. 407°; Vaill. & Boc. Miss. Sc. Mex., Poiss. p. 22 
(1874) °; Jord. & Everm. Bull. U.S. Nat. Mus. xlvi. 1896, p. 1122°. 
Centropomus appendiculatus (part.), Giinth. Trans. Zool. Soc. vi. 1868, p. 406". 
Centropomus meaxicanus, Bocourt, Ann. Se. Nat. (5) 1x. 1868, p. 90°; Vall. & Boe. o. c. p. 28, 
 t. 1. fig. 2°; Jord. & Everm. t.c. p. 1121"; Meek, Pbl. Columbian Mus. Zool. v. 1904, 
p. 199”. 
Centropomus parallelus (part.), Bouleng. Cat. Fish. 1. p. 8369 (1895) ™. 
Centropomus gabbi, Fowler, Proc. Ac. Philad. 1906, p. 428, fig. 1”. 
Centropomus heringi, Fowler, t. c. p. 425, fig. 2". 
p. 
0 
Depth of body about 34 in the length, length of head 23-27. Snout 1j-1j as long as eye, the diameter of 
which is 42-6 in the length of head ; interorbital width 7} in the length of head. Maxillary extending 
to below middle of eye, its greatest width 3-3 the diameter of eye. Praorbital acutely serrated ; 
preoperculum acutely serrated, with 2 or 3 enlarged serre at the angle; preopercular ridge with 2 spines 
at the angle. Opercular flap extending to the vertical from the origin of dorsal. 14 gill-rakers, 
including 2 or 3 rudiments, on the lower part of anterior arch. 75-88 scales in a longitudinal series, 
8-11 between middle of second dorsal and lateral line. Dorsal VIII, 1 10; third or fourth spine longest, 
i the length of head. Anal IIT 6; second spine a little longer than third, about 7 the length of the 
fish. Pectoral a little more than 3 the length of head. Ventrals about reaching the vent, which is 
situated very slightly nearer to the origin of anal than to the base of the inner ventral rays. Caudal 
peduncle about 13 as long as deep. Silvery, back darker; lateral line usually more or less blackish ; 
dorsal fins dusky. 
Hab. Atlantic Coasts of Tropical America, entering rivers: 
Mexico, Oaxaca’, San Francisco", Boca del Rio!!, El Hule!!, Perez", 
and the Rio Tonto (Gadow) in Vera Cruz; Panama, Rio Chagres (Salvin *).— 
Surinam !4; Brazil, Pernambuco !2, Bahia‘ !2; Cuba2??; Haiti4!21; Jamaica 4 12. 
