Vol. XXIII, pp. 47-48 April 19, 1910 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



THE SCALES OF THE ATHERINID FISHES. 

 BY T. D. A. COCKERELL. 



When examining the scales of various Acanthopterygians, it 

 was observed that those of the Scombrids differed so greatly 

 from those of the Percoids that it was hard to understand how 

 one could have been derived from the other. The typical 

 Percoid scale (e. g. that of Perca fluviatllis) has very strong 

 basal radii, the inferior margin being scalloped or crenulate. 

 Scales of this type may be cycloid or ctenoid, but their general 

 character remains the same. In Scomber the broad scale has 

 no basal radii whatever, and tlie lower margin is not scalloped. 

 It chanced that among some fishes of unknown locality, long- 

 preserved at the University of Colorado, I found a couple of 

 Atherinidffi. The examination of their scales at once revealed 

 the fact that they were (in respect to the squamation) exactly 

 intermediate between the Scombrids and Percoids; in fact the 

 different scales on the same fish virtually bridged the gap which 

 had seemed so great. Through the kindness of Dr. Evermann 

 and the Bureau of Fisheries, I have now been supplied with 

 four species of Atherinidffi, having authentic names and locali- 

 ties, and it seems worth wliile to report the results of their 

 examination. The Atherinid scale (from the middle of the 

 side) is broader than long, and in general very much like tliat 

 of the Scombrids. In Kirtlandia laciniata the scales from the 

 position mentioned have no basal radii, altliough the base is 

 wavy or subplicate; but the scales of the caudal peduncle show 

 strong basal radii. The diagnostic characters are as follows: 



^o 



(1.) Kirtlandia laciniata Swain. Chesapeake Bay, Va. ((Jrainpus Sta. 

 4). Scales nearly 3 mm. long, a little over 4 broad: apieal margin 

 thin, strongly irregularly crenate, with rudimentary radii; apical 



9— Proc. Biol. Soc. Wash.. Vol. XXIH, 1910. (47) 



