256 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 95 
? Piarctus (type: Myeletes brachypomus) HIGENMANN and ALLEN, Fishes of western 
South America, p. 247, 1942 (Orinoco Basin to La Plata Basin). 
A specimen collected by Dr. William Beebe in the Rio Caripe, 
near Caripito, Venezuela, April 23, 1943, was lent to me for study. 
I identify it with some uncertainty as Colossoma brachypomus because 
Cuvier (Mem. Mus. Hist. Nat. Paris, vol. 4, p. 452, pl. 22, fig. 1, 
1818) and Valenciennes (Histoire naturelle des poissons, vol. 22, 
p. 199, 1849) do not describe certain characters. This much is 
certain: It is very close to macropomus but disagrees because the 
second suborbital does not completely cover the cheek. It agrees with 
brachypomus in this respect and for this reason I tentatively identify it 
as brachypomus, but in the event it is a new form, the following de- 
scription is recorded: 
Standard length 185 mm. Greatest depth 1.9, head 3.2, anal fin 
base 3.7, dorsal fin base 4.8, and greatest postorbital length of head 
5.3, all in standard length; adipose base 5 times in dorsal fin base; 
eye 4 in the head, 2.3 in interorbital space; dorsal profile of head a 
little concave, snout short, blunt; suborbital and postorbital bones 
with low ridges; the second suborbital does not cover the cheek by a 
naked space whose width is about equal to pupil; distance from rear 
of dorsal fin base to rear of adipose fin base not quite equal to length 
of dorsal fin base; pelvic fins inserted in advance of a vertical line 
through dorsal origin; anterior rays of anal longest, the distal margin 
of anal fin a little concave; longest anal ray (first branched) a little 
longer than dorsal fin base; origin of dorsal fin a little closer to mid- 
caudal fin base than to tip of snout; adipose fin not rayed. 
The following counts were made: Dorsal rays ii, 14; anal im, 24; 
oill rakers on first gill arch 18+18; ventral serrae 38 to pelvics +21 
to anus +6 paired ones around anus; pectoral fin rays 1, 16-4, 16; 
pelvic rays 1, 7-1, 7; branched caudal rays 17; 10 or 11 scales from 
rear base of adipose fin to lateral line; scales from pelvic insertions to 
lateral line 23; number of scales from upper edge of gill opening to 
midbase of civdal fin 95; basal 4 of anal fin rays covered with small 
scales as is base of armel fin. 
Genus MYLOSSOMA Ejigenmann and Kennedy 
Mylossoma E1GENMANN and KEnnepy, Proc. Acad. Nat. Sci. Philadelphia, vol. 55, 
p. 530, Sept. 28, 1903 (type, Myletes albiscopus Cope).—EiGENMANN, Smith- 
sonian Misc. Coll., vol. 45, p. 148, Dec. 9, 1903 (type, M. albiscopus Cope). 
MYLOSSOMA ACANTHOGASTER (Valenciennes) 
PAMPANO 
Myletes acanthogaster VALENCIENNES, 7m Cuvier and Valenciennes, Histoire 
naturelle des poissons, vol. 22, p. 209, 1849 (Lagoon of Maracaibo) .— 
EIGENMANN and E1GENMANN, Proc. U.S. Nat. Mus., vol. 14, p. 60, 1891 
(Lago Maracaibo). 
