282 Field Museum of Natural History — Zo5logy, Vol. X, 



rays; adipose fin about half as far from base of upper caudal ray as from 

 base of last dorsal ray; caudal fin forked, the lower lobe the longer; 

 anal fin rather long, its origin a little behind base of last dorsal ray, 

 slightly nearer base of caudal than base of pectorals, its base notably 

 longer than head; ventral fins reaching vent, inserted midway between 

 tip of snout and base of last anal ray; pectoral fins usually reaching 

 nearly or quite to base of ventrals, inserted midway between tip of 

 lower jaw and base of ventrals. 



Color silvery, sides with an ill-defined plumbeous band. A spot or 

 short bar at shoulder, occasionally a second faint one an eye's diameter 

 behind the first. Base of caudal with a well defined black oval spot, a 

 Httle longer than deep, only slightly extended on base of caudal rays. 

 Fins mostly bright red in life. 



The most abundant species of all the fishes of Panama, occurring 

 in large numbers from the lowland waters up to the highest moimtain 

 streams, on both slopes of Panama. Our collection contains numerous 

 specimens, ranging in length from 35 to no mm. 



The Pacific slope representatives average somewhat larger in size 

 and their average depth is proportionately greater. The average depth 

 in length for 38 specimens from various localities on the Pacific slope 

 and of various sizes is 2.48. In a similar series from the Atlantic slope 

 the average depth is 2.67. 



Steindachner's name, fischeri, has long been used for this species, but 

 his figtu^es strongly indicate that he did not have this species, but 

 A. fasciatuSy as no caudal spot is indicated. The caudal spot is so 

 conspicuous in the present species that it could scarcely have been 

 overlooked. There is also nothing in Steindachner's description that 

 indicates that it was not the latter species which he had. The only 

 name that is then available is A. ruherrimus Eigenmann, of which we 

 have that author's specimens from Colombia for comparison and find 

 them to be identical with the Panama material. 



Habitat: Both slopes of Panama and both slopes of Colombia. 



23. Genus Bryconamericus Eigenmann. 



Bryconamericus Eigenmann, Ann. Carnegie Mus., IV, 1907, 139 (type 



Bryconamericus exodon Eigenmann). 



Very similar to Astyanax. Lateral line complete; caudal naked; 

 second suborbital expanded, in contact with the lower limb of pre- 

 opercle, and not leaving a naked triangle below suture between the first 

 and second suborbitals. First series of premaxillary teeth more or less 

 irregularly placed. 



