272 BIRDS or AUSTRALIA. 



of insects, upon which it solely subsists. In form and in 

 most of its habits and economy it offers some difference from 

 the typical members of the genus Geri/t/one ; and it would be 

 no great stretch of propriety to assign to it a new generic 

 appellation : the more lengthened form of its legs, the more 

 rigid structure of its primaries, and the less development of 

 the bristles at the gape are among the points in which it differs 

 from the Gerygone fusca of the brushes of New South Wales. 



The sexes are so precisely similar in plumage, and differ so 

 little in size, that dissection must be resorted to to distinguish 

 the one from the other. 



Head and back of the neck brownish grey ; back, wing- 

 coverts, rump, upper tail-coverts, margins of the primaries, 

 and the margins of the basal half of the tail-feathers bright 

 olive-green ; primaries and tail-feathers brown, the latter 

 becoming much darker towards the extremity ; under surface 

 white ; sides and vent olive-yellow ; irides wood-brown ; up- 

 per mandible greenish grey ; lower mandible white ; feet 

 blackish grey. 



Total length 3^ inches ; bill -^^ ; wing 2^ ; tail If ; tarsi f . 



Genus SMICRORNIS, Gould. 



The members of this genus are the smallest birds of the 

 Australian fauna. I have described two species, one in- 

 habiting New South Wales, and the other Port Essington ; 

 and had I characterized the bird of this form found in 

 Western Australia as distinct, I should probably not have 

 been in error. 



As it is impossible to convey a just conception of these di- 

 minutive birds by written descriptions, I must request those 

 readers who have the opportunity to consult the Plates in the 

 folio work, on which the species are represented. 



