BRYCON.—TETRAGONOPTERUS. 169 
Hab. GuaTEMALA, Rio Chisoy, Rio Usumacinta!2, Rio Motagua !2 and Lake Yzabal !2 
(Godman & Salvin). | | 
Six specimens, measuring up to 400 mm. in total length. 
The types of Brycon dentex, from Western Keuador, have 18 gill-rakers on the lower 
part of the anterior arch, 47 to 50 scales in a longitudinal series, the lower jaw shorter, 
the eye larger and the interorbital region narrower than in B. guatemalensis, and the 
body uniformly silvery. 
Gill (Proc. Ac. Philad. 1877, p. 188) has recorded B. dentex from Lake Nicaragua, 
but judging from Meek’s description (Publ. Columbian Mus., Zool. vii. 1907, p. 109) 
the Nicaraguan species is not Lrycon dente and may prove to be distinct from 
B. gquatemalensis. 
2. Brycon striatulus. 
Chalcinopsis striatulus, Kner, Sitzgsb. Bayer. Ak. 1863, p. 226'; Giinth. Cat. Fish. v. p- 837 (1864) *, 
Chalcinopsis chagrensis, Kner, 1. c. p. 338°. 
Depth of body 23 to 33 in the length, length of head 43 to 43. Snout a little longer than eye, the diameter 
of which is 4 to 43 in the length of head ; interorbital width 21 to 2? in the length of head, Maxillary 
extending nearly to below middle of eye ; lower jaw a little shorter than the upper ; premaxillary teeth 
in 4 series. 13 or 14 gill-rakers on the lower partof the anterior arch. 70 to 77 scales in a longitudinal 
series (exclusive of 4 or 5 on the basal part of the caudal), 12 to 15 between dorsal fin and lateral line, 
8 or 9 between lateral line and root of ventral fin. Dorsal 11-12; origin behind the ventrals; free edge 
nearly straight ; longest ray shorter than the head. Anal 33-39, of 3 or 4 simple and 30 to 35 branched 
rays; anterior part deep and convex, free edge emarginate. Pectoral nearly as long as or shorter than 
head, sometimes reaching the ventrals, which may extend to the anal. Caudal forked. Coloration as in 
the preceding species. 
Hab. Costa Rica, Juan Vifias and El Pozo del Rio Grande (Underwood); Panama, 
Rio Chagres 18, 
Here described from several specimens, measuring up to 230 mm. in total length. 
5. TETRAGONOPTERUS. 
Tetragonopterus, Cuv. Régne Anim. ii. p. 166 (1817); Giinth. Cat. Fish. v. p. 317 (1864) ; Jord. 
& Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 333. 
This genus comprises a large number of species from South America and a few from 
Mexico and Central America. 
Synopsis of the Mexican and Central-American Species. 
I. Interorbital width 22 to 3 in the length of head; 10 to 15 gill-rakers on the lower part of 
the anterior arch. 
Anal 25-33 (3-4/22-29); maxillary extending to below anterior edge or 
anterior part of eye; diameter of eye 3 to 3} in the length of head (in 
specimens of 65 to 120 mm.) . rr 1. eneus. 
Anal 23-29 (3-4/20-25) ; maxillary extending to below anterior } of eye; 
diameter of eye 24 to 8 in the length of head (in specimens of 65 to 
130mm.) ...... ° s 
. oe es woe eee 2. macrophthalmus. 
BIOL. CENTR.-AMER., Pisces, Yebruary 1908. Z 
e 
