Cape San Antonio, Buenos Ayres. 17 
finally, to unite the walls at and over the entrance by true 
scientific curves. Nothing but an illustration can convey an 
idea of the nest to those who are unacquainted with it ;* but 
for that purpose I may refer my readers to an example in 
the British Museum. 
Apropos of the latter (which is from the other side, the 
Banda Oriental), I may note that it seemed decidedly bigger 
than our Buenos-Ayrean nests, and that I was struck by some- 
thing wrong about the situation of the entrance—namely, 
that it was on the left-hand side instead of the right. My 
impression is that in Buenos Ayres the entrance is invariably 
on the right hand—a supposition which now remains to be 
verified. 
The nest is placed on the branch of a tree, roof of a house, 
buttress of a bridge, telegraph-post, top of a stake, or any 
similar situation. To show how regardless the archi- 
tects are of man’s presence, I may mention that it is not 
infrequent for a nest to be built on one of the posts of the 
shearing-corral, notwithstanding the attendant noise and 
bustle. Of course no concealment of the nest is ever at- 
tempted ; a satisfactory site is the only thing looked for. 
Two nests I have seen which were built on the ground—a 
most unaccountable situation. One was within fifty yards of 
a wood; but as it was also only ten from aswamp, I came to 
the conclusion that the builders had been the two laziest 
Oven-birds in all the province, and had found themselves 
unequal to the task of carryimg the building-material to 
the wood. 
The lining of the nest only consists of a little dry grass; and 
the eggs are consequently often much soiled with mud. 
Mr. Hudson has drawn attention to the attacks the Oven- 
bird has to sustain from Progne tapera, the latter always 
forming its own nest in that of the former, and not being 
content, like Leptasthenura egithaloides, to wait till the 
proper occupants have done with it. 
Four is the largest number of eggs laid, I think ; and these 
may be taken from 15th September to the end of December. 
A series of thirty-two specimens gives an average measure- 
SER. 1V.—VOL. IV. c 
