V ol. 33, pp. 25-32 July 24, 1920 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



UNUSUAL TYPES OF APPARENT GEOGRAPHIC VA- 

 RIATION IN COLOR AND OF INDIVIDUAL 

 VARIATION IN SIZE EXHIBITED 

 BY OSTINOPS DECUMANUS. 1 



BY FRANK M. CHAPMAN. 



The identification of specimens of Ostinops decumanus from 

 the Urubamba region of Peru has led to the discovery that all 

 the specimens of this species in our collection from Peru and 

 Bolivia, and most of those from Matto Grosso, southwestern 

 Brazil, present a color character shown by only one of the 

 considerable number of specimens of this species which I have 

 seen from north of the Amazon. 



Incidentally it was learned that the marked difference in 



size shown by males of this species from the same locality, 



which is apparently attributable to age, involves a striking 



difference not alone in the length but in the shape of the wing. 



The results of my studies of these two problems are presented 



below. I have to thank Mr. W. E. Clyde Todd for the loan 



of six specimens from Bolivia. 



Variation in Color. 



In general tone of color Ostinops decumanus shows but little variation 

 throughout its wide range. Specimens from west of the Andes in Colom- 

 bia and from Panama average blacker than those from east of the Andes 

 and the Colombian form has been described by Mr. W. E. Clyde Todd as 

 Ostinops decumanus melanterus (Proc. Biol. Soc. Wash., XXX, 1917, p. 

 3). Possibly the race may be valid, but I have been unable satisfactorily 

 to separate Colombian from Dutch Guiana specimens, as before remarked 

 (Bull. A. M. N. H., XXXVI, 1917, p. 624). 



1 Published by permission of the Trustees of the American Museum of Natural 

 History. 



4— Proc. Biol. Soc. Wash., Vox.. 33, 1920. (25) 



