218 BIRDS OF LA PLATA 
the Phacellodomus ruber. In its nidification it also 
comes nearest to that species. The nest is a large 
structure of sticks, eighteen inches to two feet long, 
placed upright among the twigs at the summit of a 
bush. From the top where the entrance is placed, 
a winding passage leads down to the chamber at 
the bottom of the nest; this is lined with soft dry 
grass and feathers, and four pure white eggs are laid. 
YELLOW-SPOT SPINE-TAIL 
Synallaxis sulphurifera 
Above brown, slightly olivaceous; wings blackish; lesser wing- 
coverts, margins of the feathers of the greater wing-coverts, and 
outer webs of the basal halves of the wing-feathers pale chestnut ; 
tail-feathers chestnut-brown, ends much elongated and pointed ; be- 
neath white, throat and breast mottled with grey, spot in middle of 
throat sulphur-yellow ; flanks washed with brown; bend of wing and 
under tail-coverts fulvous; length 6.5 inches. 
I HAvE found this Synallaxis, which was first de- 
scribed by Prof. Burmeister from specimens obtained 
near Buenos Ayres, in the swamps along the Plata 
river; also on the Rio Negro, in Patagonia, where, 
however, it is rare. It inhabits the dense sedge- and 
rush-beds growing in the water, where the Limnornis 
curvirostris is also found. It closely resembles that 
species in habits and language, and is also like it in 
colour and in the rather long, curved beak, sharp 
claws, stout body, and short, stiff tail. It is stationary, 
pairs for life, and lives always closely concealed in 
its chosen bed of close-growing sedge. When a 
