Most of the Osmiae of my region do not themselves prepare the dwelling destined for the laying. They want ready-made lodgings, such as the old cells and old galleries of Anthophorae and Chalicodomae. If these favourite haunts are lacking, then a hiding-place in the wall, a round hole in some bit of wood, the tube of a reed, the spiral of a dead Snail under a heap of stones are adopted, according to the tastes of the several species. The retreat selected is divided into chambers by partition-walls, after which the entrance to the dwelling receives a massive seal. That is the sum-total of the building done. For this plasterer's rather than mason's work, the Horned and the Three-horned Osmia employ soft earth. This material is a sort of dried mud, which turns to pap on the addition of a drop of water. The two Osmiae limit themselves to gathering natural soaked earth, mud in short, which they allow to dry without any special preparation on their part; and so they need deep and well-sheltered retreats, into which the rain cannot penetrate, or the work would fall to pieces. Latreille's Osmia uses different materials for her partitions and her doors. She chews the leaves of some mucilaginous plant, some mallow perhaps, and then prepares a sort of green putty with which she builds her partitions and finally closes the entrance to the dwelling. When she settles in the spacious cells of the Masked Anthophora (Anthophora personata, Illig.), the entrance to the gallery, which is wide enough to admit a man's finger, is closed with a voluminous plug of this vegetable paste. On the earthy banks, hardened by the sun, the home is then betrayed by the gaudy colour of the lid. It is as though the authorities had closed the door and affixed to it their great seals of green wax. So far then as their building-materials are concerned, the Osmiae whom I have been able to observe are divided into two classes: one building compartments with mud, the other with a green-tinted vegetable putty. To the latter belongs Latreille's Osmia. The first section includes the Horned Osmia and the Three-horned Osmia, both so remarkable for the horny tubercles on their faces.