fashions the curve which will give the spherical shape. We employ
arched centrings to support the masonry of a dome while building: the
Eumenes, more daring than we, erects her cupola without any
scaffolding.

A round orifice is contrived at the summit; and, on this orifice, rises
a funnelled mouthpiece built of pure cement. It might be the graceful
neck of some Etruscan vase. When the cell is victualled and the egg
laid, this mouthpiece is closed with a cement plug; and in this plug is
set a little pebble, one alone, no more: the ritual never varies. This
work of rustic architecture has naught to fear from the inclemency of
the weather; it does not yield to the pressure of the fingers; it
resists the knife that attempts to remove it without breaking it. Its
nipple shape and the bits of gravel wherewith it bristles all over the
outside remind one of certain cromlechs of olden time, of certain
tumuli whose domes are strewn with Cyclopean stones.

Such is the appearance of the edifice when the cell stands alone; but
the Hymenopteron nearly always fixes other domes against her first, to
the number of five, six, or more. This shortens the labour by allowing
her to use the same partition for two adjoining rooms. The original
elegant symmetry is lost and the whole now forms a cluster which, at
first sight, appears to be merely a clod of dry mud, sprinkled with
tiny pebbles. But let us examine the shapeless mass more closely and we
shall perceive the number of chambers composing the habitation with the
funnelled mouths, each quite distinct and each furnished with its
gravel stopper set in the cement.

The Chalicodoma of the Walls employs the same building methods as
Eumenes Amedei: in the courses of cement she fixes, on the outside,
small stones of minor bulk. Her work begins by being a turret of rustic
art, not without a certain prettiness; then, when the cells are placed
side by side, the whole construction degenerates into a lump governed
apparently by no architectural rule. Moreover, the Mason-bee covers her
mass of cells with a thick layer of cement, which conceals the original
rockwork edifice. The Eumenes does not resort to this general coating:
her building is too strong to need it; she leaves the pebbly facings
uncovered, as well as the entrances to the cells. The two sorts of
nests, although constructed of similar materials, are therefore easily
distinguished.

The Eumenes' cupola is the work of an artist; and t