SCLERURUS.—MARGARORNIS. 169 
description of this species, the type of which came from the same country. It is there, 
however, a rare bird, for we have never succeeded in securing another example. In 
Costa Rica it is a better known bird, for Mr. Ridgway, when compiling his monograph 
of the genus ®, had five specimens before him for examination, besides several from the 
Isthmus of Panama, whence also we have a single female bird. All these seem to 
agree fairly as to their characters and to possess white throats, each feather being edged 
with dark brown; the feathers of the breast, too, and of the sides of the neck have 
lighter centres contrasting with darker edges. These points and the greater size and 
less rufous rump of S. guatemalensis readily serve to distinguish it from 8. mexicanus. 
Regarding its extension southwards into Western Ecuador we are in some doubt, as 
the birds from that country attributed to 8. guatemalensis by Mr. Sclater in his recently 
published Catalogue appear to us to belong to a distinct species*. They are much 
darker in general colour, and have longer bills (1:2 inch). The breast is less rufous 
and the rump darker. It is possible these birds may belong to Dr. Cabanis’s S. oliva- 
ceus, but without examining the type of that bird it would be unsafe to pronounce a 
definite opinion. 
S. olivaceus has been placed as a synonym of S. brunneus by Mr. Sclater, but is given 
a distinct position by Mr. Ridgway, but neither author has examined the type. 
Subfam. MARGARORNITHINA fF. 
MARGARORNIS. 
Margarornis, Reichenbach, Handb. p. 179 (1858) ; Scl. Cat. Birds Brit. Mus. xv. p. 121. 
Margarornis contains six species, of which two occur within our region in Costa 
Rica and the State of Panama. The others are fonnd in the Andes from Venezuela 
and Colombia to Bolivia, none occurring in Guiana or any portion of Brazil. 
The bill of Margarornis (M. brunnescens) is slender, the culmen slightly curved, and 
the tomia without a subterminal notch; the nostrils are overhung bya membrane, 
leaving the opening a long slit on the lower edge of the nasal fossa. The toes are rather 
long, the outer and middle toes united towards the base, the inner toe more free, the 
hallux long, its claw curved much as in those of the other toes. The tail is not 
nearly so stiff as in Glyphorhynchus aud Sittosomus, but the shafts of the feathers 
project beyond the webs as in all the Dendrocolaptine. 
*  Sclerurus brunneus,” specimen 6 (Scl. Cat. Birds Brit. Mus. xv. p. 116), from the Balzar Mountains, is 
precisely like ‘‘S. guatemalensis,” specimen c, from Santa Rita. It is to these two birds that the above note 
refers. 
+ Antea, p. 146. 
BIOL. CENTR.-AMER., Aves, Vol. II., September 1891. 22 
