4 Mr. R. Ridgway on the Genus Micrastur. 
6 . Wing 6*50, tail 6'80. Adult. Tail crossed by 2 bars of pale 
brownish grey. Above uniform dark plumbeous, the tail darker 
and wings browner; throat light grey; rest of lower parts white, 
barred everywhere with dusky, these bars very narrow and dis¬ 
tant on the flanks and crissum . M. pelzelni. 
B. Outer toe not longer (sometimes shorter) than the inner. 
7. Wing 7T0-7*75, tail 6*80-7-00. 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 crissum 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 tibiee and flanks also immaculate. 
M. concentricus. 
The following table will serve to elucidate the synonymy 
of the species, as understood by me :— 
1875 
{Ridgway). 
1874 
{Sharpe). 
1873 
{Ridgway). 
1869 
{Scl. df Salvin). 
1865 
{Relzeln). 
1 . melanoleucus 
2 . mirandollii 
8 . guerilla 
4. zonothorax 
5. ruficollis 
6 . pelzelni 
7 . concentricus 
semitorquatus 
mirandollii 
guerilla 
zonothorax 
ruficollis | 
semitorquatus 
mirandollii 
ruficollis, pt. 
ruficollis, pt. 
leucauchen 
ruficollis, pt. 
semitorquatus 
mirandollii 
guerilla 
zonothorax 
leucauchen 
ruficollis 
gilvicollis (pt.) 
gilvicollis 
brachypterus 
macrorhynchus 
guerilla 
xanthothorax 
gilvicollis 
concentricus 
gilvicollis 
concentricus 
The following is a description of M. pelzelni :— 
Micrastur pelzelni, Ridgway. 
Sp. Gh. Outer toe decidedly longer than the inner; tail 
shorter than the wing. Adult £* above uniform (continu¬ 
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 Godman, from Sarayacu, Upper 
Ucayali, Peruvian Amazons, collected by E. Bartlett, August 2, I 860 . 
