Vol. XXIII, pp 61-64 April 19, 1910 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



THE SCALES OF THE CLUPEID FISHES. 

 BY T. D. A. COCKERELL. 



The scales of an ordinary Clupeid are very thin, more or less 

 circular, and very finely sculptured. In Alosa sapidissima they 

 vary from longitudinally to transversely oval on different jmrts 

 of the same fish, while the larger and best developed scales 

 (about 16 mm. each way) are subquadrate. A closer examina- 

 tion of the scales of A. sapidissima shuws the following features: 

 Apical field sharply separated from the rest, much broader than 

 long, without circuli, bvit with very numerous (2^-3 in a mm.) 

 delicate radii or grooves, which scallop the apical margin, and 

 have between them on that margin a series of low lobes or 

 angles, making the scale obscurely ctenoid; these lobules or 

 denticulations can also be seen more or less clearly repeated 

 once or twice in the submarginal area, marking periods of 

 cessation of growth, and indicating the process whereby the 

 rows of spines in the apical field of a Beryx scale are formed. 

 Delicate lines of growth can be seen also in the other parts of 

 the scale, but they have nothing to do with the circuli, wbich 

 exist as exceedingly fine lines (about six in 170 ,'0 all over the 

 scale except in the apical field. These circuli are transverse in 

 the middle and reach the lateral margins very obliquely. The 

 basal region of the scale is inclined to be thrown into three 

 radiating folds, suggesting a slight approach to the basal radii 

 of the Percoids, etc., but these folds are not marked by any 

 signs of radii. 



The most striking feature of the scale remains to be men- 

 tioned. Everywhere except in the apical field, at variable 

 intervals averaging perhaps half a mm., there are grooved lines 

 crossing the scale, approximately following the circuli, bent on 

 the elevations between the basal grooves or folds, and curving 



13— Pruu. Bioi.. Soc. Wash., Vol. XXIII. I'JIO. (61) 



