roofs of houses, or in trees, as is the case with the other species. The
female lays only two eggs, which are milk-white, long, and peaked at the
small end. It is a very lively bird, rising early and retiring to rest
late, and is observed, in the height of summer, to be on the wing
sixteen hours a day. Like the martin, they are no songsters, having only
one harsh, screaming note, which, however, I cannot consider
disagreeable. It is never heard but in the most lovely summer weather,
and, consequently, the sound occasions in my mind a pleasing association
of ideas, which I like to indulge. If by any accident they settle upon
the ground, they find great difficulty in rising, on account of the
shortness of their legs and the length of their wings: neither can they
walk conveniently, they only crawl along.

_Louisa_. They seem, in many respects different in their habits from the
other species you have mentioned, mamma: how may we distinguish them by
their outward appearance?

_Mrs. B_. The peculiar formation of the foot plainly discriminates them,
for it is so disposed, as to carry all its four toes forward; which
clearly accounts for the difficulty it finds in walking. As they arrive
later, so they retire sooner than the others, being seldom seen after
the middle of August. Are you not tired, my children, with my long
account of these birds?

"Oh no, dear mamma: pray tell us something about sand-martins too,"
exclaimed each of the children; "we shall then be able to distinguish
each of the four species of British _hirundines_."

Mrs. Bernard assured them, she would willingly comply with their
request, as far as she was able to do it: "but," added she, "it is