A fourth class of this kind[1] of insect is the bombyx,[2] which is a native of Assyria, and is of larger size than any of those which have been previously mentioned. They construct their nests of a kind of mud which has the appearance of salt, and then fasten them to a stone, where they become so hard, that it is scarcely possible to penetrate them with a dart-even. In these nests they make wax, in larger quantities than bees, and the grub which they then produce is larger.