which, in some respects, agrees with the one just described. During the mid-day heat, a copious and refreshing supply of limpid dew, or rather rain, may be seen to fall from the branches of the trees, which is caused by the larvæ of Cicada (Aphrophora) Goudoti. The larvæ are found in clusters, enveloped by a whitish froth very similar to the cuckoo spit. They are in constant agitation, and pressing eagerly upon each other in their attempts to apply themselves to the surface of the bark, from which they extract the sap in such quantity as to maintain their bodies in a state of saturated humidity. This sap is afterward discharged, and forms drops of small size, which are gradually collected into larger drops, and appears to escape from the bodies of the larvæ with a rapidity proportioned to the action of the solar rays. The activity of the larvæ is, in fact, increased in a corresponding degree with the increase in the atmospheric temperature. Towards evening, and when the influence of the solar rays is sensibly diminished, the production of the fluid, thus singularly secreted, is partially suspended, and the drops fall slowly; as the night advances a few rare and tardy drops are heard at distant intervals, until at last they altogether cease, to be renewed with the first rays of the morning sun. When fifty or a hundred such clusters of larvæ are placed, as often happens, on the same tree, it may well be imagined that the secretion may become sufficiently copious to assume the appearance of actual rain. In a mass of sixty or seventy individuals, about half grown, the sun being powerful, the drops were very large, and fell in quick succession. The observer estimated, that setting aside the loss by evaporation, and by the animals which drank from the vessel, he could have filled a bottle, containing about a quart, in an hour and a half. The limpid character of the water encouraging the belief that it was free from any pernicious qualities, he tasted

it, and found no unpleasant flavour: he also gave it to some fowl, without producing any inconvenience. When exposed to the air, however, it speedily loses its transparency. Even after the insect has obtained its perfect state, it continues to emit, at different intervals, small drops of liquid.

The Chinese are indebted to a species of cicada for a white wax, which is much valued. The larva of the Cicada limbata forms a sort of grease, which adheres to the branches of trees and hardens into wax. In autumn the natives scrape it from off the trees, melt, purify, and form it into cakes. It is white and glossy in appearance, and, when mixed with oil, is used to make candles, and is said to be superior to the common wax, for use. Sir George Staunton informs us, that he saw them busily employed upon the small branches of a shrub. They did not much exceed the domestic fly in size, and were of a very singular structure. They were in every part covered with a kind of white powder, and the branches they most frequented were entirely whitened by this substance strewed over them.

CHAPTER XIV.

NATURAL HISTORY OF THE EPHEMERA OR MAYFLY.

An account of the Larva and Pupa-Their Differences-The formation of their Fins or Breathing apparatus-The Larva of another kind of Ephemera-Their Habitations-Habits of the perfect Insect-Manner of changing its Skin-Of laying their Eggs, &c.

THE Insect whose habits are now to be described, has long been known to the naturalist as a delicate and fragile creature; while the moralist has at all

times found an apt emblem of human life in the history of this "being of a day." To some, indeed, even this short length of perfect life is not allowed, since their existence does not extend beyond a few hours, which is sufficiently long to enable the insect to soar from the waters into the air, to perpetuate its kind and die.

The ephemera or Mayfly, however, undergoes the same number of metamorphoses as the rest of insects. As worm and nymph it is an inhabitant of the waters, where it acquires its growth so slowly, that with regard to the length of these portions of its life, it has been at least as well treated as the rest of insects. Swammerdam asserts that the ephemeræ continue two or three years in their larva and pupæ states; and that it is only when they have attained to the utmost perfection of which their organization is susceptible that they so speedily perish.

As long as the insect is an inhabitant of the

moved with the rapidity of lightning, described as fins by some; while, on the contrary, others have regarded them as oars; and the little insect thus fashioned has been compared to an antique galley. But a moment's consideration will suffice to rectify the error; for it is observed, that the time during which the supposed fins or oars are in the greatest agitation, is that at which the larva is in repose.

The oars or fins, however, are the instruments by which the insect breathes its lungs. To those who are not familiar with the study of comparative anatomy, it will appear strange that the lungs should be placed on the outside of the body of any animal, and that the function of respiration should be performed by a rotatory motion of little tubes. Nevertheless,

the gills of fishes present a familiar example of the essential parts of a similar fact; these are the breathing organs of this class of animals, and in them the blood is vitalized by the contact of such air as is contained in the water, as the latter fluid is admitted or ejected by the alternate opening and shutting of these organs.

In examining the structure of these organs in the different kinds of ephemeræ, the reader will be astonished to find such a variety of form in parts destined to perform the same function. In the two following figures the construction of this singular apparatus is admirably shown. Fig. 1 represents

one of the trachea or breathing-tubes magnified, which has been removed from that kind of ephemera that has been likened to a galley. A common trunk gives rise to two large branches, from each of which smaller ones, of a conical form, are given off diametrically opposite each other and at equal distances. VOL. II.-S