62 
Mr. H. Durnford on the Birds of 
( 21. Thamnophilus argentinus^ Cab.; Ibis^ 1877^ p. 183. 
The nest of this bird is a very slight flimsy structure of 
grass^ lined with the finer fibres of the same material and a 
little hair. It is placed about three feet from the ground, 
and suspended from the twigs of a bush, which pass through 
some portion of the nest, and is situated in reed-beds and 
swampy places. 
I "22. Heleothreptus anomalus (Gould); Nomencl. p. 97. 
On the 31st March 1877 I was given this bird, shot the 
previous day near Quilmes. It is the only specimen I have 
seen here, and the museum does not possess an example. My 
friend informed me that he flushed it from a clump of thistles. 
Its stomach was full of insect-remains, and on dissection it 
proved a female. 
[It is a female of the rather rare Caprimulgine form Heleo¬ 
threptus anomalus, which we have not previously seen from 
so far south. Natterer obtained it in several localities in 
Southern Brazil (see Pelzeln, Orn. Bras. p. 12).— Edd.] 
23. Picus MiXTUs, Bodd.; Nomencl. p. 99. 
Partially resident, but more numerous in the summer than 
the winter. The male is rather more brightly coloured than 
the female, and the red feathers on his head are more nu¬ 
merous than in the other sex. 
24. Butorides cyanurus (Vieill.); Nomencl. p. 125. 
Though I have never shot this bird I have often observed 
it in reed-beds near Lujan bridge, and less frequently at Punta 
Lara. It frequents the same sort of places as Ardelta invo- 
lucris and Nycticorax ohscurus, though it is not nearly so 
numerous as either of these birds, and, owing to its shyness, 
I have not yet been able to obtain a specimen. 
—- 25. Ardetta involucris (Vieill.); Ibis, 1877, p. 189. 
On the 29th October 1876 I found a nest of this bird in a 
small lagoon amongst a clump of tall rushes, and just above 
the water. It was entirely composed of short pieces of these 
rushes, arranged with their points meeting in the centre, and 
not more than seven inches in diameter, altogether a very 
