The colours of this bird are altogether plain; but it is remarkable for its very singular nest, which is so large, as to form a feature in the woodland scenery of Bahia, the only part of Brazil where I observed it: the nest is built in low trees, formed externally of dried sticks, without any neatness, and is usually three or four feet long, resembling at a distance a thick twist of bean stalks thrown in the branches by accident: sometimes two of these nests appear as if joined together, and there is an opening on the side, besides one at the top. The sexes are generally seen near the nest, uttering a shrill, incessant, monotonous chirp, particularly in the morning and evening. I never could bring myself to tear one of their nests to pieces, merely to see its construction. All the birds of this genus are stated by Professor Temminck to be natives either of the old world, or of the southern hemisphere; but the observations I have made, lead me to think otherwise. Two of the generic types M. Temminck has given, are the same as those I have selected; these birds are now before me; the other (_Le Capolier_,) is so like the species here figured, that (judging from Le Vaillant's plate) they might easily pass for the same bird. Two other species, with characters perfectly resembling _M. garrulus_, are likewise found in Brazil. From a consideration, therefore, of the affinities and habits of these birds, I conceive they may constitute a very natural genus, closely allied to _Sylvia_, having very compressed bills, short wings, russet coloured plumage, with soft and generally long tails, and building rather large and cylindrical nests. On the other hand, if the whole of the birds mentioned by P. Temminck are retained in the genus, I apprehend it will become entirely artificial; inasmuch as it will include not only the birds above mentioned, but the _Motacilla superba_, and a large non-descript bird from New Holland, the size of a thrush, which in habit, though not in characters, resembles a shrike. M. Vieillot first proposed this genus, but his definition is so short and obscure, that little can be gained from it. The slight sketch in the distance, introduced in the plate, will give some idea of the singular nest of this bird. * * * * * Pl. 139 [Illustration] SYLVIA plumbea, _Grey-backed Warbler._ * * * * * GENERIC CHARACTER. _Rostri recti, tenuis, basi altiore quam latiore, mandibula superiori aliquando emarginata, inferiori recta. Nares basales, laterales, membrana partim tectae. Crura longiora digito medio, qui digito exteriori ad basin annectitur. Ungue posteriore mediocri, digito posteriore breviore et arcuato. Remigum pinna prima brevissima aliquando caret. Tectrices remigibus multo breviores._ Temm.