4 Mr. R. Ridgway on the Genus Micrastur. 



6. Wing 6-50, tail 6 30. Adult. Tail crossed by 2 bars of pale 



brownish grey. Above uniform dark plumbeous, the tail dai-ker 

 and wings bro^^^ler ; throat light grey ; rest of lower parts white, 

 barred everywhere with dusky, tliese bars very narrow and dis- 

 tant on the flanks and crissiim 31. pelzelni. 



B. Outer toe not longer (sometimes shorter) than the inner. 



7. Wing 7-10-7-75, tail C-30-7-00. Adult. Tail-bands 1-4, narrow, 



white ; upper parts dull plumbeous, the tail darker, and the 

 wings browner ; throat greyish white ; other lower parts white, 

 the crissutn immaculate, the other portions barred with plum- 

 beous. Young. Similar, but a whitish crescent behind the ear- 

 coverts, the upper parts browner, the lower tinged with ochra- 

 ceous, and the tibiae and flanks also immaculate. 



M. concentricus. 



The following table will serve to elucidate the synonymy 

 of the species^ as understood by me : — 



The following is a description of M. pelzelni : — 



MiCRASTUR PELZELNI, Ridgwav. 



Sp. Ch. Outer toe decidedly longer than the inner; tail 

 shorter than the wing. Adult (^* above uniform (continii- 

 ous) dark plumbeous. Tail darker, narrowly tipped with 

 white, and crossed by two narrow bands of dull brownish 

 grey, becoming white on inner webs. Sides of head and 

 neck plumbeous grey ; throat light grey ; rest of lower parts 

 white, marked everywhere with narrow transverse bars of 

 dark plumbeous or slate, these bars widest on the breast 

 (where they are narrower than the white interspaces), and 



* Type of species in Mas. Salvin and Godnian, from Sarayacu, Upper 

 Ucayali, Peruvian Amazons, collected by E. Bartlett, August 2, 1865. 



