The first to hatch is the Seven-pronged Resin-bee (Anthidium septemdentatum). We see her, in the month of April, lumbering along to the rubbish-heaps in the quarries and the low boundary-walls, in search of her Snail-shell. She is a contemporary of the Three-horned Osmia, who begins operations in the last week of April, and often occupies the same stone-heap, settling in the next shell. She is well-advised to start work early and to be on neighbourly terms with the Osmia when the latter is building; in fact, we shall soon see the terrible dangers to which that same proximity exposes her dilatory rival in resin-work, Anthidium bellicosum. The shell adopted in the great majority of cases is that of the Common Snail, Helix aspersa. It is sometimes of full size, sometimes half-developed. Helix nemoralis and H. caespitum, which are much smaller, also supply suitable lodgings; and this would as surely apply to any shell of sufficient capacity, if the places which I explore possessed others, as witness a nest which my son Emile has sent me from somewhere near Marseilles. This time, the Resin-bee is settled in Helix algira, the most remarkable of our land-shells because of the width and regularity of its spiral, which is copied from that of the Ammonites. This magnificent nest, a perfect specimen of both the Snail's work and the Bee's, deserves description before any other. For a distance of three centimetres (1.17 inches.--Translator's Note.) from the mouth, the last spiral whorl contains nothing. At this inconsiderable depth, a partition is clearly seen. The moderate diameter of the passage accounts for the Anthidium's choice of this site to which our eye can penetrate. In the common Snail-shell, whose cavity widens rapidly, the insect establishes itself much farther back, so that, in order to see the terminal partition, we must, as I have said, make a lateral inlet. The position of this boundary-ceiling, which may come farther forward or farther back, depends on the variable diameter of the passage. The cells of the cocoons require a certain length and a certain breadth, which the mother finds by going higher up or lower down in the spiral, according to the shape of the shell. When the diameter is suitable, the last whorl is occupied up to the orifice, where the final lid appears, absolutely exposed to view. This is the case with the adult Helix nemoralis and H. caespitum, and also with the young Common Snail. We will not linger at present over this peculiarity, the importance of which will become manifest shortly.