Todd — Studies in the Tyrannidce. 



189 



Measurements. 



Range. — From Central Argentina northward through Paraguay, western 

 Matto Grosso, BoHvia, Peru, and Ecuador (east of the Andes), to Vene- 

 zuela (including the Dutch West Indies), thence eastward to Guiana, and 

 westward to northern Colombia. 



Remarks. — The above description is based on specimens in fairly fresh 

 plumage and average condition. A great deal of variation obtains in the 

 series examined — more than suffices in other species of Myiarchus to dis- 

 criminate racial differences, but it is individual and seasonal, certainly not 

 geographical. In worn plumage the upper parts fade out to brownish, 

 while in perfectly fresh dress there is often an olivaceous cast to the feathers 

 above, and the yellow below is purer. A bird from Colombia (No. 38,829, 

 Collection Carnegie Museum) is very pale above (citrine drab), while 

 another from Argentina (No. 141,744, Collection American Museum of 

 Natural History) is unusually dark (near dark olive), and between these 

 extremes there is every possible degree of variation. We note, too, that 

 the age of the specimens themselves has considerable to do with their shade 

 of color. A series from Matto Grosso, Brazil, collected by Herbert H. 

 Smith in 1885-86, are markedly duller and paler than specimens in com- 

 parable condition secured in the same general region in more recent years, 

 and the same is true of the series from the Santa Marta region collected by 

 Mr. W. W. Brown in 1898-99 as compared with Mr. M. A. Carriker, Jr.'s 

 later material from the same place. Consequently care must be exercised 

 in comparing such specimens. 



Eliminating young and worn specimens, therefore, and using only such 

 as are in fact comparable, we can find no sufficient ground for separating a 

 series from the Caribbean coast region of Colombia from another from 



