Carriker : List of the Birds of Costa Rica. 597 



c. White bars above broader and more conspicuous, lower parts with much 

 more white than black (Pacific slope). 



Thamnophilus doliatus pacificus, $ . 

 cc. White bars above narrow, black and white about evenly divided below; 

 (Carribean slope). Thamnophilus doliatus mexicanus, $ . 



bb. Upper parts never barred with white, and never black, except sometimes 

 on pileum. 

 c. Under parts uniformly buff-ochi^ceous, or bright cinnamon-brown. 

 d. Bright chestnut-brown above, sides of head and nuchal collar streaked 

 with black and buffy. 



Thamnophilus doliatus pacificus and mexicanus, 9 • 

 dd. Upper parts dull grayish-olive or sepia-brown. 



e. Under parts bright cinnamon-brown; size larger (wing, 75 mm.). 



/. Upper parts uniform light sepia; wing-coverts dusky brown, 



tipped with chestnut. Gymnocichla nudiceps erratilis, 9 • 



ff. Upper parts dark sepia, pileum paler; wings brighter brown, 



coverts blackish, without lighter tips. 



Gymnocichla cheiroleuca, 9 • 

 ee. Under parts bright buff-ochraceous, under tail-coverts ruddier; 

 above dull grayish-olive; smaller (wing, 55). 



Myrmotherula menetriesi schisticolor , 9 • 

 cc. Under parts variously colored, but never as above. 



d. Under tail-coverts dark brown or chestnut, and may or may not be 

 a different color from abdomen, but never mixed with white. 

 e. Under parts (except flanks and vent) uniform slaty-black or pure 

 white. 

 /. Under parts pure white, above rich chestnut-rufous. 



Thamnophilus transandeanus, 9 • 

 ff. Under parts uniform slaty-black, also pileum. 



g. Lesser and middle wing-coverts black in abrupt contrast to 

 the brown quills, and tipped with white; concealed white on 

 back; black of crown extending over upper back. 



Myrmeciza Icemosticla, $ . 

 gg. Wing-coverts concolorous with wing and back (chestnut- 

 brown); no concealed white on back, and black confined 

 to pileum. 

 h. Lower parts more slaty (Pacific). 



Myrmeciza occidentalis, $ . 

 hh. Lower parts more black (Carribean). 



Myrmeciza exsul, $ . 

 ee. Under parts variouly colored, but never slaty-black or white. 

 /. Throat deep black (not slaty), unmarked. 



g. Whole chest and breast bright chestnut-rufous; upper tail- 

 coverts concolorous with lower, in abrupt contrast to the rich 

 olive-sepia of back. Formicarius rufipectus, $ , 9 • 



gg. Chest dark ashy-olive or sooty-gray, slightly darker than breast 

 and abdomen; upper parts rich seal-brown or bistre. 



