tant in
collecting, who is a very accurate person, found a nest of the
sparrow of this country (Zonotrichia matutina), with one egg in it
larger than the others, and of a different colour and shape. In
North America there is another species of Molothrus (M. pecoris),
which has a similar cuckoo-like habit, and which is most closely
allied in every respect to the species from the Plata, even in such
trifling peculiarities as standing on the backs of cattle; it
differs only in being a little smaller, and in its plumage and eggs
being of a slightly different shade of colour. This close agreement
in structure and habits, in representative species coming from
opposite quarters of a great continent, always strikes one as
interesting, though of common occurrence.

Mr. Swainson has well remarked, that with the exception of the
Molothrus pecoris, to which must be added the M. niger, the cuckoos
are the only birds which can be called truly parasitical; namely,
such as "fasten themselves, as it were, on another living animal,
whose animal heat brings their young into life, whose food they
live upon, and whose death would cause theirs during the period of
infancy." (3/8. "Magazine of Zoology and Botany" volume 1 page
217.) It is remarkable that some of the species, but not all, both
of the Cuckoo and Molothrus should agree in this one strange habit
of their parasitical propagation, whilst opposed to each other in
almost every other habit: the molothrus, like our starling, is
eminently sociable, and lives on the open plains without art or
disguise: the cuckoo, as every one knows, is a singularly shy bird;
it frequents the most retired thickets, and feeds on fruit and
caterpillars. In structure also these two genera are widely removed
from each other. Many theories, even phrenological theories, have
been advanced to explain the origin of the cuckoo laying its eggs
in other birds' nests. M. Prevost alone, I think, has thrown light
by his observations on this puzzle: he finds that the female
cuckoo, which, according to most observers, lays at least from four
to six eggs, must pair with the male each time after laying only
one or two eggs. (3/9. Read before the Academy of Sciences in
Paris. L'Institut 1834 page 418.) Now, if the cuckoo was obliged to
sit on her own eggs, she would either have to sit on all together,
and therefore leave those first laid so long, that they probably
would become addled; or she would have to hatch separate