492 PROCEEDINGS OF THE ACADEMY OF [Oct. 



A EEVIEW OF THE GENUS PIAYA Lesson. 



BY WITMER STONE. 



While rearranging the Cuckoos in the collection of the Academy 

 of Natural Sciences my attention was attracted to the type specimen 

 of Piaya macroura Gambel. The apparent omission of this species 

 from Dr. Bowdler Sharpe's Hand List of Birds led me to make a critical 

 study of the genus, the results of which are embodied in the present 

 paper. 



I am under obligations to the United States National Museum 

 through Dr. Charles W. Richmond, and to the American Museum of 

 Natural History through Mr. Frank M. Chapman, for the loan of large 

 series of specimens of the genus, without which my investigation would 

 not have been possible. The material loaned by these institutions, 

 together with that in the Academy's Museum, numbers 259 specimens 

 distributed as follows: Mexico, 64; Central America, 59; Panama, 13; 

 Colombia, 26; Venezuela, 18; Ecuador, 8; Brazil, 32; Guiana, 6; 

 Bohvia, 2; Peru, 4; Paraguay, 2; Trinidad, 8. 



The genus Piaya includes two very well-marked species, P. melano- 

 gastra and P. rutilus, and a number of alhed geographic races which 

 have generally been combined under the name P. cayana. 



The first two offer but few difficulties, and it is the cayana group that 

 has caused confusion in the nomenclature of the genus. The forms 

 of Piaija caijana may be roughly divided into three groups according 

 to the color of the upper surface. In group (1) it is bright ferruginous t 

 (2) bay inclining to chestnut; (3) walnut brown tinged with chestnut. 

 Beginning at the northern part of the range of the genus, we have in 

 western Mexico a large form of the ferruginous group (mexicana), 

 while in eastern Mexico, extending throughout Central America and 

 Panama, is a totally different form of the chestnut-backed group 

 (mehleri). The individuals are quite uniform over this large area, 

 with the exception of the size of the bill, which is smaller in Mexican 

 and Yucatan birds than in those from Nicaragua and Costa Rica. 



In the Cauca river valley of Colombia is a slightly different form 

 (caucce), in which the flanks as well as the crissum are black, this 



1 All colors are based on Ridgway's nomenclature of colors. 



