THE SCALES OF THE AFRICAN CHARACINID FISHES 



By T. D. a. COCKEREL! 

 University of Colorado, Boulder, Colo. 



(With Two Plates) 



As primitive relatives of the Cyprinid2e, confined to the Neotropical 

 and Ethiopian regions, the Characinidse (or Characidae) are of more 

 than usual interest to students of the evolution of fishes. After 

 having spent much time in the investigation of the scales of the 

 Cyprinids, I was very anxious to see those of the Characinids, and 

 the opportunity v\^as offered during a recent visit to the British Mu- 

 seum. For all the material used in the preparation of the present 

 paper I am indebted to the kindness of Dr. G. A. Boulenger, who 

 has in his custody at the British Museum a truly wonderful col- 

 lection of African freshwater fishes, as every ichthyologist knows. 

 It was an extraordinary privilege to have access to these rich mate- 

 rials, which had been gathered with so much difficulty and sometimes 

 danger, and had formed the basis of classical researches. 



The sculpture of an ordinary fish-scale includes two important 

 elements, the circuli and the radii. The circuli are circular lines, 

 sometimes referred to as "lines of growth," while the radii are 

 lines or grooves radiating outward from the nuclear area, which 

 may or may not be in the center of the scale, but is practically 

 always in the middle line. The most primitive fish with scales 

 resembling those of the Teleosts is Amia calva, and through the 

 kindness of Dr. B. W. Evermann I have been able to examine speci- 

 mens of this fish from the Yellow River at Plymouth, Indiana. 

 There are no radii, but the scales are made up of longitudinal strands 

 which are really separable elements, and will fray out basally. These 

 appear on the scale as very fine striae which in the apical field are 

 directed toward a broad rugulose nuclear area. There is no doubt, 

 I think, that these are the circuli of the Teleosts, and indeed they are 

 nearly repeated in various forms, though I know no scale which as 

 a whole can be said to closely resemble that of Amia} This view 



' I placed a scale of Polypterus endlicheri (from the White Nile) in acid to 

 ascertain the structure of the organic basis, which proved to be rather scanty 

 and of a sponge-like consistency. 



Smithsonian Miscellaneous Collections, Vol. 56, No. 1 



