SCLERUErS.— MAEGAEOEJSIS. 



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 Eica it is a better known bird, for Mr. Eidgway, 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 S. mexicanus. 



Eegarding its extension southwards into Western Ecuador we are in some doubt, as 

 the birds from that country attributed to S. 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. oUvaceus has been placed as a synonym of S. hrunneus by Mr. Sclater, but is given 

 a distinct position by Mr. Eidgway, but neither author has examined the type. 



Subfam. MABGAROBNITRmJEf. 



MAEGAEOENIS. 



Margarornis, Reichenbach, Handb. p. 179 (1853) ; Scl. Cat. Birds Brit. Mus. xv. p. 121. 



Margarornis contains six species, of which two occur within our region in Costa 

 Eica and the State of Panama. The others are found in the Andes from Venezuela 

 and Colombia to Bolivia, none occurring in Guiana or any portion of Brazil. 



The bill of Margarornis {M. hrunnescens) is slender, the culmen slightly curved, and 

 the tomia without a subterminal notch ; the nostrils are overhung by a 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 Qlyphorhynchus and Sittosomus, but the shafts of the feathers 

 project beyond the webs as in all the Dendrocolaptinae. 



* " Sclerurus hrunneus," specimen h (Scl. Cat. Birds Brit. Mus. xv. p. 116), from the Balzar Mountains, is 

 precisely like " S. guatemalensis," specimen c, from Santa £ita. It is to these two birds that the above note 

 refers. 



t Antea, p. 146. 



BIOL. CENTE.-AMEB., Aves, Vol. II., September 1891. 22 



