rienced eye, it is a chance splash of mud and nothing more.

This outer covering dries as quickly as do our hydraulic cements; and
the nest is now almost as hard as a stone. It takes a knife with a
strong blade to break open the edifice. And I would add, in conclusion,
that, under its final form, the nest in no way recalls the original
work, so much so that one would imagine the cells of the start, those
elegant turrets covered with stucco-work, and the dome of the finish,
looking like a mere lump of mud, to be the product of two different
species. But scrape away the crust of cement and we shall easily
recognize the cells below and their layers of tiny pebbles.

Instead of building a brand-new nest, on a hitherto unoccupied boulder,
the Mason-bee of the Walls is always glad to make use of the old nests
which have lasted through the year without suffering any damage worth
mentioning. The mortar dome has remained very much what it was at the
beginning, thanks to the solidity of the masonry, only it is perforated
with a number of round holes, corresponding with the chambers, the cells
inhabited by past generations of larvae. Dwellings such as these, which
need only a little repair to put them in good condition, save a great
deal of time and trouble; and the Mason-bees look out for them and do
not decide to build new nests except when the old ones are wanting.

From one and the same dome there issue several inhabitants, brothers and
sisters, ruddy males and black females, all the offspring of the same
Bee. The males lead a careless existence, know nothing of work and
do not return to the clay houses except for a brief moment to woo the
ladies; nor do they reck of the deserted cabin. What they want is the
nectar in the flower-cups, not mortar to mix between their mandibles.
There remain the young mothers, who alone are charged with the future
of the family. To which of them will the inheritance of the old nest
revert? As sisters, they have equal rights to it: so our code would
decide, since the day when it shook itself free of the old savage
right of primogeniture. But the Mason-bees have not yet got beyond the
primitive basis of property, the right of the first occupant.

When, therefore, the laying-time is at hand, the Bee takes possession of
the first vacant nest that suits her and settles there; and woe to any
sister or neighbour who shall henceforth dare to contest her ownership.
Hot pursuits and fierce blows will so