Other species of this genus use resin in place of cotton as their working material. Among these are _Anthidium septemdentatum_ and _A. bellicosum_. The former species chooses an old snail-shell as its nidus, and constructs in it near the top a barrier of resin, so as to shut off the part where the whorl is too small; then beneath the shelter of this barrier it accumulates a store of honey-pollen, deposits an egg, and completes the cell by another transverse barrier of resin; two such cells are usually constructed in one snail-shell, and below them is placed a barricade of small miscellaneous articles, similar to what we have described in speaking of the cotton-working species of the genus. This bee completes its metamorphosis, and is ready to leave the cell in early spring. Its congener, _A. bellicosum_, has the same habits, with the exception that it works later in the year, and is thus exposed to a great danger, that very frequently proves fatal to it. This bee does not completely occupy the snail-shell with its cells, but leaves the lower and larger portion of the shell vacant. Now, there is another bee, a species of _Osmia_, that is also fond of snail-shells as a nesting-place, and that affects the same localities as the _A. septemdentatum_; very often the _Osmia_ selects for its nest the vacant part of a shell, the other part of which is occupied by the _Anthidium_; the result of this is that when the metamorphoses are completed, the latter bee is unable to effect its escape, and {48}thus perishes in the cell. Fabre further states with regard to these interesting bees, that no structural differences of the feet or mandibles can be detected between the workers in cotton and the workers in resin; and he also says that in the case where two cells are constructed in one snail-shell, a male individual is produced from the cell of the greater capacity, and a female from the other.