96 BIRDS OF LA PLATA 
at 
possessed it only to account for the strange attraction 
such nests have for them, which seems like a recur- 
rence to an ancestral habit. 
SCREAMING COW-BIRD 
Molothrus rufoaxillaris 
Silky black glossed with purple; wings and tail with a slight 
greenish gloss; bill and feet black; length 8 inches. Female the 
same; slightly smaller. 
Tuts bird has no vulgar name, not being distin- 
guished from the Common Cow-bird by the country 
people. The English name of Screaming Cow-bird, 
which I have bestowed on it, will I think commend 
itself as appropriate to those who observe it, for they 
will always and at any distance be able to distinguish 
it from the species it resembles so nearly by listening 
to its impetuous screaming notes, so unlike anything 
in the language of the Common Cow-bird. 
The Screaming Cow-bird is larger than the allied 
species. The female is less than the male in size, but 
in colour they are alike, the entire plumage being 
deep blue-black, glossy, with purple reflections, and 
under the wing at the joint there is a small rufous 
spot. The beak is very stout, the plumage loose, 
with a strong musky smell; the cesophagus re- 
markably wide. 
It is far less common than the other species of 
Molothrus, but not rare, and ranges south to the 
