THE PHILOSOPHY OF BIRDS NESTS. 228a 
‘swift (Tachornis phznicobea) inhabited exclusively 
the palm trees in a few districts in the island. A 
colony then established themselves in two cocoa-nut 
palms in Spanish Town, and remained there till 1857, 
when one tree was blown down, and the other stripped 
of its foliage. Instead of now seeking out other palm 
trees, the swifts drove out the swallows who built in 
the Piazza of the House of Assembly, and took pos- 
session of it, building their nests on the tops of the 
end walls and at the angles formed by the beams and 
joists, a place which they continue to occupy in con- 
siderable numbers. It is remarked that here they form 
their nest with much less elaboration than when built 
in the palms, probably from being less exposed. 
A still more curious example of change and im- 
provement in nest building was published by Mr. F. 
A. Pouchet, in the tenth number of the Comptes 
Rendus for 1870, just as the first edition of this work 
appeared. Forty years ago M. Pouchet had himself 
collected nests of the House-Martin or Window-. 
Swallow (Hirundo urbica) from old buildings at Rouen, 
and deposited them in the museum of that city. On 
recently obtaining some more nests he was surprised, 
on comparing them with the old ones, to find that 
they exhibited a decided change of form and structure. 
This led him to investigate the matter more closely. 
The changed nests had been obtained from houses in 
a newly erected quarter of the city, and he found that 
all the nests in the newly-built streets were of the 
new form. But on visiting the churches and older 
