84 Fretp MusEum or Naturat History — ZoéLocy, Vor. X. 
two oblique black bars on each lobe; pectorals and ventrals nearly 
black mesially. 
Tuyra River basin. 
Brycon argenteus sp. nov. 
Type No. 7588, F. M. N. H.; length 230 mm., Rio Aruza, Aruza, 
Panama. 
Head 3.7 to 4.0; depth 3.2 to 3.6; D. 10; A. 24 to 26; scales 42 to 45. 
Body elongate, moderately compressed; the profile nearly straight; 
mouth large, the upper jaw slightly the longer, margin of lower lip 
between the first and second rows of premaxillary teeth; eye 3.2 to 3.5 
in head; snout 3.8 to 4.2; maxillary 2.2 to 2.4; maxillary teeth 16 or 17 
on each side; gill-rakers 9 + 12 or 13; origin of dorsal slightly behind 
that of ventrals; pectorals 1.5 in head; caudal peduncle 2.7 to 2.9. 
Color silvery, darker above; sides without lines or bands; a large 
black spot on caudal peduncle extending on base of caudal rays. 
Pacific slope of eastern Panama... 
Brycon petrosus sp. nov. 
Type No. 7589, F. M. N. H.; length 285 mm.; Upper Chagres. 
Panama. | 
Head 3.7 to 3.9; depth 3.5 to 3.7; D. 9 or 10; A. 30 to 32; scales 
52 to 58. 
Body elongate, robust, moderately compressed; profile concave; 
mouth large, the upper jaw the longer, the second row of teeth at margin 
of lower lip; eye 3.6 to 4.0 in head; snout 3.4 to 3.6; maxillary reaching 
nearly to middle of eye, its length 2.1 to 2.3 in head; maxillary teeth 
12 or 13 on each side; gill-rakers 10 to 12 + 12 or 13; origin of dorsal 
slightly in advance of middle of ventrals, about midway between base 
of caudal and nostril; pectorals 1.4 in head; depth of caudal pedunele 
2.8 to 2.9 in head. 
Color uniform silvery; sides without dark lines or bands; a ta 
caudal spot extending on base of caudal rays. 
Chagres River basin. 
Reeboides macrolepis sp. nov. 
Type No. 7590, F. M. N. H.; length 56 mm.; Rio Cupe, Boca de 
Cupe, Panama. 
Head 4.3 to 4.4; depth 3.4 to 3.8; D. I, 7 or 8; A. II, 49 to 54; scales 
48. 
Body elongate, much compressed; profile nearly straight; back not 
