5. CATHARUS. 289 



The female apparently only differs from the male in having the 

 upper mandible a dark horn-colour ; iu the abraded plumage of 

 summer some of the russet and rusty brown disappears, and the 

 back approaches olive-brown. Birds of the year do not differ from 

 adults, except in showing ochraceous tips to some of the median 

 wmg-coverts. Young in first plurnaye have pale ochraceous centres 

 and obscure dark terminal bands to the small feathers of the 

 upper parts ; the lesser and median wing-coverts have ochraceous 

 tips ; and the slate-grey of the underparts is replaced by very pale 

 brown, each feather having a darker brown transverse terminal 

 band. 



The Common Central-American Thrush-Robin is a resident in the 

 highlands of the extreme south of Mexico, Guatemala, and Costa 

 Eica. Examples from the latter locality are slightly less russet in 

 the brown of the upper parts, and have the under tail-coverts less 

 suffused with brown. 



a, h. Ad. st. Mexico. Purchased. 



I propose to call the intermediate form 



7. Catharus birchalli. 



In the general colour of the upper parts this form scarcely differs 

 from C. melpomene, except that the rich rusty brown on the 

 outer webs of the wing-coverts is replaced by russet-brown scarcely 

 richer than the back. It is, however, very difficult to separate the 

 least rusty-winged Central-American form from the most rusty- 

 winged Colombian form. From C. ariruntiirostris this form may 

 be distinguished by the general colour of the upper parts being 

 russet-brown instead of olive-brown, though here again the most 

 rufous examples of C. aurantiirostris are scarcely separable 

 from the least rufous examples of the intermediate form. Bill 

 orange. Wing-formula as in C. aurantiirostris. Legs, feet, and 

 claws yellow. Length of wing 3-3 to 3-06 inches, tail 2* 6 to 

 2-35, culmen 0-72 to 0-7, tarsus 1-2 to 1-1, bastard primary 1-05 to 

 0-So. 



Birchall's Thrush-Robin has been received from Bogota and in 

 collections supposed to come from the Oronoco valley. 



a, b. Ad. sk. Oronoco valley. H. Seebohm, Esq. [P.]. 



8. Catharus aurantiirostris. 



Turdus aurantiirostris, llarthuih, liev. vt Mug. Zool. 1850, p. 158; 



Jarcf. Cuntr. Orn. 18o(), p. f^U, pi. Ixxii. 

 Catharus imniaculatus, /)'/). Cunsp. i. p. 278 (1850). 

 Turdus imiuacidatiis, Bi>.,fde Bp. Coiisp. i. p. 278 (1850). 

 Catharus aurantiirostris (Uartktub), Sclater, P. Z. S. 1859, p. 323 ; 

 Sclat. ^- Sa/v. Nomend. Av. Neotr. p. 1 (1873). 

 VOL. V. u 



