1873.] 75 [Ridgway. 



B. — Inner toe appreciably longer than the outer. 



5. Wing less than 8.00. Tail shorter than the wing. 

 Lower tail coverts immaculate white. M. concentricus. 



SYNOPSIS OF THE SPECIES OF MICRASTUR. 



A. — Inner toe appreciably shorter than the outer. Tail longer than 

 the wing (except in M. mirandollei) . 



a. Wing 9.00 or more; only four outer primaries with inner 



webs appreciably sinuated (constant?). 



1. M. semitorquatus. Wing, 9 .70-11.20 ; tail, 9.80-13.00. 



Above plumbeous-black, or blackish brown, inter- 

 rupted by a nuchal collar of white or ochraceous. 

 Adult. Lower parts immaculate white or ochraceous. 

 Young. Lower parts barred, or transversely spotted, 

 with blackish. Hab. Whole of Continental Tropical 

 America. 



2. M. mirandollei. Wing, 9.00-9.30; tail, 7.80-9.00. 



Above uniform slaty plumbeous, without a lighter 

 nuchal collar. Lower parts white, the breast some- 

 times with faint crescentic marks of grayish. Young 

 not seen. Hab. Brazil to Panama. 



b. Wing less than 8.00 , five outer primaries with inner webs 



appreciably sinuated. 



3. M. ruficollis. Wing, 6.30-7.30; tail, 7.00-8.00; tar- 



sus, 2.20-2.35. Adult without a light nuchal collar ; 

 crissum transversely barred. Adult. Above varying 

 from slate-color to reddish sepia ; head and neck uni- 

 form grayish, the throat lighter ; breast usually more 

 or less rufescent. Beneath white, everywhere with 

 regular, continuous, narrow bars of dusky slate. 

 Young. Above dark sepia; pileum darker, and sep- 

 arated by a nearly concealed whitish nuchal collar. 

 Beneath, including the throat, pale ochraceous, or 

 ochraceous- white, the breast, sides and tibias with 

 narrow transverse bars of dusky brown, varying with 

 the individual in number and distinctness. Hab. 

 Whole of Continental Tropical America. 



4. M. leucauchen. Wing, 6. 20-6.60 ; tail, 7.20-7.50 ; 



tarsus, 2.00-2.10. Adult with a nuchal collar of white 

 spots; crissum transversely barred. Chin, throat, 



