The grubs of several of the numerous species of may-fly (_Ephemera_) excavate burrows for themselves in soft earth, on the banks of rivers and canals, under the level of the water, an operation well described by Scopoli, Swammerdam, and Réaumur. The excavations are always proportioned to the size of the inhabitant; and consequently, when it is young and small, the hole is proportionally small, though, with respect to extent, it is always at least double the length of its body. The hole, being under the level of the river, is always filled with water, so that the grub swims in its native element, and while it is secure from being preyed upon by fishes, it has its own food within easy reach. It feeds, in fact, if we may judge from its _egesta_, upon the slime or moistened clay with which its hole is lined. In the bank of the stream at Lee, in Kent, we had occasion to take up an old willow stump, which, previous to its being driven into the bank, had been perforated in numerous places by the caterpillar of the goat-moth (_Cossus ligniperda_). From having been driven amongst the moist clay, these perforations became filled with it, and the grubs of the ephemeræ found them very suitable for their habitation: for the wood supplied a more secure protection than if their galleries had been excavated in the clay. In these holes of the wood we found several empty, and some in which were full-grown grubs. (J. R.) The architecture of the grub of a pretty genus of beetles, known to entomologists by the name of _Cincindela_, is peculiarly interesting. It was first made known by the eminent French naturalists, Geoffroy, Desmarest, and Latreille. This grub, which may be met with during spring, and also in summer and autumn, in sandy places, is long, cylindric, soft whitish, and furnished with six scaly brown feet. The head is of a square form, with six or eight eyes, and very large in proportion to the body. They have strong jaws, and on the eighth joint of the body there are two fleshy tubercles, thickly clothed with reddish hairs, and armed with a recurved horny spine, the whole giving to the grub the form of the letter Z. [Illustration: Nest of the Grubs of Ephemeræ. A, The Grub. B, Perforations in a river bank. C, One laid open to show the parallel structure.] [Illustration: Nests of Ephemeræ in holes of Cossus.]