SYLVIIDZ. A5 
2. Cinclus ardesiacus. 
Cinclus ardesiacus, Salv. Ibis, 1867, p. 121, t. 2*; Lawr. Ann. Lyc. N. Y. ix. p. 92°; v. Frantz. 
J. f. Orn. 1869, p. 290°. 
Cinereus, subtus dilutior, capite toto fuscescente, gula albicantiore; alis et cauda fusco-nigris, alarum tectri- 
cibus et secundariis cinereo marginatis ; ciliis albis; rostro nigro, pedibus flavis. Long. tota 5:5, ale 3-2, 
caude 1°6, tarsi 1-2, rostri a rictu 0-9. (Descr. fem. ex Cordillera de Tolé, in statu Panamensi. Mus. 
nostr.) 
3 juv. corpore subtus albido, alarum tectricibus albo terminatis. (Descr. exempl. ex eodem loco. Mus. nostr.) 
Hab. Costa Rica, Dota Mountains (Zeledon 2%); Panama, Cordillera de Tolé (Arcé?). 
Of this southern form of Cinclus mexicanus but little is known. Since the receipt 
of the two specimens from the Cordillera de Tolé, which formed the basis of the 
original description, no others have reached us from that part of the country. It 
has, however, been detected in Costa Rica in the Dota Mountains ??; and Mr. Sclater 
has a skin obtained in the same country. 
Cinclus ardesiacus is a close ally of C. mexicanus. It is, however, of a greyer tint ; 
and though of smaller size, its bill fully equals that of its congener in length. ‘The 
legs, too, of the type specimen are yellow; but this may indicate immaturity, as the 
legs of young birds of C’. mewxicanus are described as of that colour. 
Fam. SYLVIIDA. 
Subfam. SAXICOLINA. 
SIALIA. 
Sialia, Swainson, Zool. Journ. iii. p. 173 (1827). (Type Motacilla statis, Linn.) 
This small genus of three species is a purely Nearctic one, two of its members passing, 
however, beyond the southern boundary as far as Southern Mexico and Honduras. 
Its relationship seems to be nearest to the Old-World genus Sazicola, from which it 
chiefly differs in its much shorter tarsi and more thickened bill, besides possessing a 
totally different character of coloration in the plumage. The young have a spotted 
first plumage as in the typical Turdide; and with that family Stalia and, indeed, 
Saxicola have a very close relationship. 
1. Sialia sialis. 
Motacilla sialis, Linn. Syst. Nat. i. p. 386°. 
Sialia sialis, Baird, Rev. Am. B.i. p. 627; Baird, Brew. & Ridgw. N. Am. B. i. p. 62°; Coues, 
B. of the N.W. p. 13*; Sennett, Bull. Geol. & Geogr. Surv. iv. p.6°; Merrill, Pr. U.S. 
Nat. Mus. i. p. 120°; Gundl. Orn. Cub. p. 61". 
