Vol. XXIII, pp. 111-114 July 23, 1910 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



r" 



UJ L I E 



OX THE SCALES OF SOME MALACOPTERYGIAN ^^^ 



FISHES. 



BY T. D. A. COCKERELL. 



In the endeavor to trace the evolution and relationsliip of tlie 

 scales of the Teleosts, and through these of the fishes themselves, 

 it was obviously necessary to become acquainted with as man}- 

 as possible of the families and genera of that great assemblage 

 classed by Boulenger as Malacopterygii, and placed by him at 

 the base of the Teleostean system. Many of the smaller Mala- 

 copterygian families, however, consist of fishes which are rare 

 and difficult to obtain, and I could have made little progress 

 but for the great kindness of Dr. G. A. Boulenger in sending 

 me scales of Notopterus, Heterotis, Pantodoyi, Phractolasmus and 

 Knenia, ''^ aud of Dr. D. S. .Jordan in contributing scales of CJii- 

 rocentrus. In some future paper I hope to figure all these scales, 

 but the results of their examination are so interesting that they 

 deserve to be put on record without delay. 



Oslcoghssidx. 



Heterotis niloticus Ehrenb. Large oval scales with the exposed portion 

 thick and corrugated, with a more or less vermiform sculpture; base 

 rounded or narrowed (as in 3Iormyrid;e), not at all truncate; radial 

 sculpture throughout a large-meshed network, quite in the manner of 

 the Mormyrid?e, but better developed, and covering the basal as well 

 as apical area; circuli resolved into granules, but in the lateral field 

 remaining as well formed though monilifoim lines. This is the only 

 scale known to me, outside of the Mormyridae, having the true ]\Ior- 

 myrid form and pattern. Are we to see in the Osteoglossids the 

 ancient type from which the IMormyrids came? There is a curious 

 superficial similarity in the fishes themselves; thus compare Mormy- 

 rops with Osteoglossum, Dapedoglossus with Petrocephalus. The dif- 



' Dr. Boulenger notes that all are from the middle of the side, above the lateral line 

 29— Proc. Biol. Soc. Wash., Vol. XXI II. UHO. (Ill) 



