Vol. XXIII, pp. 91-94 May 27, 1910 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



ON THE NATURE OF THE TEETH IN CTENOID 



SCALES. 



BY T. D. A. COCKERELL AND EVELYN V. MOORE. 



In the course of our examination of a number of ctenoid 

 scales, Ave have come to the conclusion that the teeth arise 

 through the modification of the apical ends of vertical circuli, 

 i.e., circuli which in the apical region retain their primitive ver- 

 tical position. It is not evident that they have anything to do 

 with the radii. In very highly specialized ctenoid scales, such 

 as those of Dlstlchodus among the Characinidee, or Rhinogobius 

 among the Gobiidse (these two genera, though so little related, 

 have the same kind of apical teeth), the teeth form a separate 

 fringe which appears to have no intimate connection with the 

 rest of the scale. From the study of such as these, the true 

 nature of the ctenoid feature could not be made out, but it is 



mm 



Fig. 1. 



Scale of Neomxnis griscus, showing at left. 



connection of lateral with apical circuli. 



admirably shown in the Characinid, Citharidium ansorgii, in 



which the comparatively few and remote teeth are seen to be 



continuations of vertical apical circuli, supplemented by the con- 



21— Proc. Biol. Soc. Wash., Vol. XXIII. 1910. (i>l) 



