286 Frerp MusEeum or Naturat History — Zoéroey, Vor. X. 
of anal decurrent, with several interpolated rows; origin of dorsal fin 
about midway between tip of snout and base of caudal; adipose fin well 
developed, over posterior fifth of anal, a little nearer base of caudal than 
base of last dorsal ray; caudal fin forked, the lobes of about equal length; 
anal fin rather long, its base 2.8 to 3.25 in length of body, its origin 
under posterior rays of dorsal, midway between posterior margin of 
eye and base of caudal; ventral fins scarcely reaching origin of anal, 
inserted an eye’s diameter nearer tip of snout than base of last anal 
ray; pectoral fins reaching to or slightly past base of ventrals, only 
slightly shorter than head. 
Color silvery; sides with a plumbeous lateral band, darkest poste- 
riorly; faint humeral and opercular spots present; a black band extend- 
ing from base of caudal to tips of middle caudal rays. 
Of this species there are 66 specimens, ranging from 40 to 80 mm. in 
length, in the present collection. All were taken in the Rio Tuyra 
Basin. We have designated as the type a specimen, 65 mm. in length, 
from the mouth of the Rio Yape. 
Considerable variation in the depth of the body and the number of 
teeth on the maxillary is apparent among our specimens, but these 
appear to be only individual variations. 
This species differs from H.decurrens (Eigenmann), of which we have 
examined a paratype, in the fewer scales in the lateral line, in the slightly 
shorter and more posteriorly placed anal. In H. decurrens there are 44 
scales in the lateral line, 31 to 33 anal rays and the origin of the anal 
is in front of the middle of base of dorsal. This species is also closely 
related to H. guppii (Regan) from which it apparently differs in having 
one more row of scales between the lateral line and base of dorsal, also 
one more row between base of anal and lateral line; the rows of scales 
in H. guppit above and in advance of anal are less strongly decurrent 
and the interpolated rows are fewer. 
Habitat: Rio Tuyra Basin, Panama. 
25. Genus Hyphessobrycon Durbin. 
Hyphessobrycon Durbin, in Eigenmann, Bull. Mus. Comp. Zool., LII, 
1908, 100 (type Hemigrammus compressus Meek). 
Dermatocheir Durbin, Ann. Carnegie Mus., 1909, 55 (type Dermatocheir 
catablepta Durbin). 
Body short, compressed, the back elevated; head short; premaxillary 
teeth in 2 series; maxillary teeth, if present, crowded on the upper 
anterior angle; lateral line incomplete; caudal fin naked; the lobes equal 
or subequal, 
