NATURAL SCIENCES OP PHILADELPHIA. 481 



beneath immaculate white or ochraceous. Young: (1) Beneath 

 spotted or barred with dusky, or (2) with the feathers bordered 

 with grayish. (B) Adult: Above varying from plumbeous to 

 rufous ; beneath marked with regular, ray-like bars of dusky and 

 white except on the throat and sometimes (in M. concentricus) 

 the crissum and anal region. Young: Throat and half-crescent 

 behind the ear coverts, white ; lower parts white, with or without 

 coarse bars of dusky. 



They may be distinguished by the following differential charac- 

 ters : 



Fie. 8. 



M. pelzelni. Nat. size. 



A. Outer toe decidedly longer than the inner. (Fig. 8.) 



a. Size large (wing more than 8.00). 



1. Tail longer than the wing (wing 9.70-11.70, tail 9.60-13.00). Above 

 black with a nuchal collar of white or ochraceous. Entire Inter- 

 tropical Region, except Andean district. M. melanoleucus. 



2. Tail shorter than the wing (wing 8.80-9.30, tail 7.80-9.00). Above 

 plumbeous, without a nuchal collar. Costa Rica to Brazil. 



M. mirandolii. 



b. Size small (wing less than 8.00). 



3. Wing, 6.50-7.10; tail, 6.90-7.50; tarsus, 2.20-2.50; middle toe, 

 1.10-1.25. Tail crossed by 3-6 white bars. 1 Adult: Tail crossed 

 by 3-4 bars of white. Above uniform plumbeous or chocolate, the 

 head and neck plumbeous. Throat light-gray ; jugulum, breast, and 

 entire lower parts barred with white and dusky. Young : Above 

 dark clove-brown, sometimes indistinctly barred or spotted with 

 rusty. Beneath white or buff, with coarse bars of dusky (rarely im- 

 maculate). Middle America, south to Ecuador. M. guerilla. 



4. Wing, 6.90-7.50 ; tail, 7.00-8.40 ; tarsus, 2.20-2.45; middle toe, 1.15- 

 1.25. Adult [rufous phase): Above rusty-chocolate, becoming gray- 

 ish-brown on the crown ; throat light chocolate ; jugulum, and entire 

 other lower parts transversely barred with dusky and white. Tail 

 crossed by 4-5 bars of white. Young : Above dark sooty brown, 

 indistinctly barred with light rusty ; crown and nape sooty black. 

 Tail crossed with 6-7 bars of white. Lower parts buflf'y white, or 

 buff, without rufous tinge on breast. Venezuela and Columbia. 



Z. zonothorax. 



1 The terminal bar is not counted in these diagnoses. 



