154 MNIOTILTID A. 
As to the Yucatan bird we cannot speak positively. Mr. Lawrence calls it 
G. poliocephala*®; but that was when G. caninucha had not been recognized as a 
distinct race. A specimen from British Honduras must be referred to G. caninucha, 
and it is improbable that the Yucatan bird differs from it. 
The figure is taken from a Costa-Rica specimen. 
6. Geothlypis poliocephala. (Tab. IX. fig. 3.) 
Geothlypis poliocephala, Baird, Rev. Am. B. i. p. 225+; Salv. Ibis, 1872, p. 147 et seq.’; Baird, 
Brew. & Ridgw. N. Am. B.i. p. 296°; Lawr. Mem. Bost. Soc. N. H. ii. p. 269°. 
Trichas delafieldi, Scl. P. Z. 8S. 1856, p. 293°? 
Precedenti persimilis, sed ciliis albis forsan distinguenda. 
Hab. Mexico, Mazatlan (Grayson 1°). 
When Prof. Baird first described this species! he associated together the specimens 
from North-western Mexico and from Guatemala, at the same time pointing out certain 
differences between them. ‘The chief of these consisted in the former having white 
eyelids, not observed in the Guatemalan bird. On the strength of these differences 
Mr. Ridgway separated the two birds, calling the Mexican one G. poliocephala, and the 
Guatemalan one G. caninucha®. After examining the types, which were kindly sent us 
from Washington, we feel great doubts as to whether the two birds can be kept separate, 
even as races. Some of our Guatemalan specimens have white feathers in the eyelids, 
as we have already noticed 2; and thus one of the chief distinctions is not entirely trust- 
worthy. Moreover the skins are none of them in good fresh condition, rendering a 
comparison of their colours not altogether satisfactory. However, as Mr. Ridgway has 
gone so far as to separate the two birds, we deem it best to follow in the lines of his 
arrangement, giving a figure of each bird, the strong likeness between the two being, it 
must be confessed, very obvious. 
The only specimens of the true G. poliocephala that we have seen are the types 
procured at Mazatlan by Grayson, one of which is now figured; but it is not improbable 
that M. Sallé’s skins, called by Mr. Sclater Trichas delafieldi in his first paper on 
Mexican birds®, really belonged to this species. TZ. delafieldi of Audubon is now 
supposed to be the same as 7. eguinoctialis, the Mexican representative of which, 
unrecognized in 1856, would be either G. poliocephala or G. caninucha, but more 
probably the former. 
B. Gula cinerea. 
7. Geothlypis philadelphia. 
Sylvia philadelphia, Wils. Am. Orn. ii. p. 101, t. 14. f. 6°. 
Geothlypis philadelphia, Lawr. Aun. Lyc. N. H. vii. p. 822’, ix. p. 94°; Dresser, Ibis, 1865, p. 476°; 
Frantz. J. f. Orn, 1869, p. 294°; Wyatt, Ibis, 1871, p. 322°; Salv. Ibis, 1872, p. 1497; 
