are now breaking up the
laying into groups of two, a female and a male, as required by the
conditions of the lodging.

I have only once found Latreille's Osmia established in the nest of the
Masked Anthophora. She had occupied but a small number of cells, because
the others were not free, being inhabited by the Anthophora. The cells
in question were divided into three storeys by partitions of green
mortar; the lower storey was occupied by a female, the two others by
males, with smaller cocoons.

I came to an even more remarkable example. Two Anthidia of my district,
A. septemdentatum, LATR., and A. bellicosum, LEP., adopt as the home of
their offspring the empty shells of different snails: Helix aspersa, H.
algira, H. nemoralis, H. caespitum. The first-named, the Common Snail,
is the most often used, under the stone-heaps and in the crevices of old
walls. Both Anthidia colonize only the second whorl of the spiral. The
central part is too small and remains unoccupied. Even so with the front
whorl, the largest, which is left completely empty, so much so that, on
looking through the opening, it is impossible to tell whether the shell
does or does not contain the Bee's nest. We have to break this last
whorl if we would perceive the curious nest tucked away in the spiral.

We then find first a transversal partition, formed of tiny bits of
gravel cemented by a putty made from resin, which is collected in fresh
drops from the oxycedrus and the Aleppo pine. Beyond this is a stout
barricade made up of rubbish of all kinds: bits of gravel, scraps of
earth, juniper-needles, the catkins of the conifers, small shells,
dried excretions of Snails. Next come a partition of pure resin, a large
cocoon in a roomy chamber, a second partition of pure resin and, lastly,
a smaller cocoon in a narrow chamber. The inequality of the two cells is
the necessary consequence of the shape of the shell, whose inner space
gains rapidly in width as the spiral gets nearer to the orifice. Thus,
by the mere general arrangement of the home and without any work on the
Bee's part beyond some slender partitions, a large room is marked out in
front and a much smaller room at the back.

By a very remarkable exception, which I have mentioned casually
elsewhere, the males of the genus Anthidium are generally larger than
the females; and this is the case with the two species in particular
that divide the Snail's spiral with resin partitions. I collected some
do