Plumbeous Bush-Tit 509 
Aiken found a nest in the foothills north-east of Cafion 
City, containing five eggs, May 9th, 1876 ; D. P. Ingraham 
took three sets of eggs near Beulah, at the foot of the 
Wet Mountains, in the summer of 1897, and W. Cross 
a nest with six eggs at Glenwood Springs, but no further 
details are given by Cooke. 
Nests taken by Lieut. Benson, U.S.A., in southern 
Arizona (Bendire, “ P.U.S.N. Mus.,” XI., p. 557) were 
gourd-like in shape, woven into and supported by twigs 
of scrub oak ; they were made of sage-bush leaves, spider 
web, moss and lichen, and thickly lined with soft small 
feathers ; the entrance was on the side near the top. 
The eggs were pure white in colour, and ovate in 
shape ; they were four to six in number, and measured 
*538 x °40. 
Family SYLVIIDA. 
This family contains the true Warblers chiefly met 
with in the Old World. They are very closely allied 
to the Thrushes, from which they can best be distin- 
guished by the fact that the young are unspotted, and 
that most of them undergo a double moult in spring 
and autumn. 
The United States genera can be easily distinguished 
by their small size—wing under 3—their slender bill 
more or less notched at the tip, their wing with ten 
primaries, the outer of which is barely or considerably 
less than half the next, and by their plain blueish or olive- 
greenish plumage. 
Key or THE GENERA. 
A. Tarsus booted ; crown with a yellow or reddish patch. 
. Regulus, p. 510. 
B. Tarsus scutellate ; no crown-patch ; plumage chiefly slaty. 
Polioptila, p. 513. 
