Vol. XXVIII, pp. 151-160 September 21, 1915 



PROCEEDINGS 



or THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



SCALES OF PANAMA FISHES. 

 BY T. D. A. COCKERELL. 



The year before last, when Dr. S. E. Meek was working at the 

 U. S. National Museum on his collection of Panama fishes, he 

 very kindly allowed me to take scales of a large number of 

 species. The present report deals with this material, including 

 also a few species collected by others in the Republic of Panama 

 or the Canal Zone. Whenever the collector's name is not given, 

 it is to be understood that the material was obtained by Messrs. 

 Meek and Hildebrand. 



The following key enumerates the species studied, and shows 

 how they may be separated. With few exceptions, a single 

 normal (not regenerated) scale from the middle of the side will 

 serve to distinguish a species from all the others in the col- 

 lection. 



Scales cycloid ( obscurely ctenoid in Gerres) 1. 



Scales ctenoid 16. 



1. Circuli and radii entirely transverse (Clupeidae) 



Opisthonema libertate Giinther. (Tabogal.) 

 Circuli transverse, basal only; no radii, but basal margin lobed, and 

 radial folds faintly indicated (Atherinidae) 



Atherina arxa Jordan & Gilbert. (Porto Bello. ) 



Circuli concentric ; radii absent 2. 



Circuli concentric, or rarely (Opisthopterus) essentially transverse; 

 radii present, not transverse, or (Gastropelecus) only partly so . 3. 



2. Circuli complete; scales very minute (Belonidse) 



Tylosurus scapularis Jordan & Gilbert. (Balboa.) 

 Circuli absent from apical part of scales (Characidse) 



Roeboides guatemalensis Gunther. (Gatun R. ) 

 .3. Scales elongate ; with very numerous radii all around (Rypticidse) 



Rypticus nigripinnis Gill. (Corazal.) 

 Radii not all around 4. 



32— Pboc. Biol. Soc. Wash., Vol. XXVIII. 1915. (151) 



