NATURAL SCIENCES OF PHILADELPHIA. 489 



4. MlCRASTUIt ZONOTHORAX. 



Climacocercus zonothorax, Cabanis, Journ. fur Orn. 1865, 40G. 



Micrastur zonothorax, Scl. and Salv., P. Z. S. 1809, 3G6 ; Nom. Av. 



Neotr. 1873, 120. Gray, Hand-List B., I, 1869, 31. Sharpe, Cat. 



Diurn. Ace. Br. Mus. 1874, 79. 



Hob. New Granada and Venezuela. 



Sp. Char. Wing 6.90-7.50 ; tail 7.60-8.40 ; tarsus 2.20-2.45 ; 

 middle toe 1.15-1.25. 



Adult (brown phase) : Above rusty-chocolate, becoming gradu- 

 ally less reddish on the head, the crown being dull grayish-brown. 

 Tail black, narrowly tipped with white, and crossed by 3-4 

 narrow bars of white. Whole throat light chocolate, like the 

 cheeks; remaining lower parts, including the jugulum, and lining 

 of the wing finely barred with clear dark slate and white, the 

 white bars broader posteriorly but much narrower than the slaty 

 ones on the jugulum. 



Young: Above dark sooty-brown, much tinged with rusty, and 

 indistinctly barred or spotted transversely with lighter rusty over 

 the whole surface. Crown and nape sooty-black, separated from 

 the dusky-brown of the back by a more or less distinct nuchal 

 collar of white or buff. Tail black, narrowly tipped with white, 

 and crossed with 5-6 narrow bands of white. Lower parts buffy- 

 white or deep buff, sometimes immaculate, but generally more or 

 less barred with brownish-clusky ; the throat white, sending up a 

 branch behind the brown ear-coverts, in form of half a crescent. 



Remarks. This form appears to be distinct from both 31. 

 guerilla and 31. ruficollis, between which it is somewhat inter- 

 mediate, though larger than either; but the differences are much 

 harder to define than they are to perceive. The series before us 

 is very small, while only one specimen is an adult; to make the 

 material still more unsatisfactory, two of the three young birds 

 are not full-grown, so that measurements would be useless. 



The 31. zonothorax is considerabl}' larger than either of its 

 allies, the tail especially being longer ; the old bird resembles 

 most that of 31. ruficollis, but the jugulum is barred slate and 

 white, like the breast, instead of being covered by a rufous patch ; 

 the head, too, is browner. The young bird is in colors more like 

 that of M. guerilla, lacking entirely any rufous wash on the 

 breast, and having the upper parts distinctly spotted with light 

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