Cockerell: Scales of Characinid Fishes. 10.'} 



I. hinnicnUitiis. 



(a) polylepis, ahranioides, potarocnsis and nuilator. 



(b) mucronatiis, giiianensis and esscquibensis. 

 Brycoiiamcriciis hyphessus Eigenmann. Small, thin, more or less semi- 

 circular scales, with a \evy distinct pattern, as well shown in 

 Plate XXVI, fig. 8. A strong curved line goes across the scale; 

 below it are widely spaced circuli, abo\e it no sculpture whatever. 

 The condition strongly recalls certain scales of Clupeids, but there 

 is little resemblance in detail. 



Creatochanes Giinther. 

 The scales of Creatochanes have a characteristic form, well shown 

 in Plate XXVI, fig. 9, and Plate XXVII, fig. i. The outline is much 

 like that of Leporinus. At first sight there seems little or no resem- 

 blance to Bryconamericus, but closer inspection shows that, as in B. 

 hyphessus, the apical area is free from circuli, and the circuli end 

 abruptly at a line passing from the nucleus to the margin. The 

 bounding line, however, is very broadly V-shaped instead of gently 

 curved, and is not marked by anything more than the terminations 

 of the circuli. Another difTerence is found in the presence of apical 

 radii in Creatochanes. According to these characters, Bryconamericus 

 could be derived from Creatochanes, but hardly the reverse. 

 Creatochanes melaniirus (Bloch) (Plate XXVII, fig. i). The scales 

 have a diameter of about 23^2 mm.; there are two strong apical radii 

 forming a sort of U (compare Aphyocharax), and occasionally one 

 or two additional. 

 Creatochanes affinis Giinther (Plate XXVI, fig. 9). Similar, but the 

 radii evanescent, sometimes wholly absent. In both species the 

 nuclear area is leticulate, with the reticulations more or less broken 

 down, becoming labyrinthiform. 

 Creatochanes caudomaculatus Giinther. Scales about four mm. broad, 

 of the same general type, the circuli fine, and the strong radii two 

 to eight, arranged in a fan-like manner. When only two radii are 

 present they usually form a V rather than a U. The nuclear area is 

 broadly ornamented with a minute ^•ermiform sculpture, consisting 

 of irregular bent and curved short strands, and intermingled dots, 

 with dots also scattered over the basal half of the radial field. All 

 this nuclear sculpture is derived from broken-up circuli; compare 

 the structures in the Cyi)rinids Barbichthys and Osteochiliis, as 

 figured in Zool. Anzeiger, Sept. 27, 1910, pp. 252-253. 



