Meths; whilst others, whose wings stand erect, and are placed at a distance from each other, with prominent eyes, feed upon llIuscw, or flies.

The second genus, Epheniera, is remarkable for the shortness of its existence in the fly state, which sometimes does not exceed half an hour; though some of them, whilst cater pillars, live in the water for three whole years, where earth and clay seem to be their only nourishment. The larva, when ready to quit that state, rises to the surface of the water, and getting instantaneously rid of its skin, becomes a chrysalis. This chrysalis is furnished with wings, which convey it to the first tree within reach, upon which it settles, and, in the same moment, quits a second skin, and undergoes its last change to a perfect :ephemera. Those species that answer this description, live some days in the larva and chrysalis state They have fringes of hair, which answer the purpose of fins. In both states their ahdomen is terminated by three threads. Whilst larva, they scoop themselves out dwellings iii the banks of rivers, in the form of tubes made like syphons; the one end serving for an entrance, the other affording them an outlet. The banks of some rivers are often full of these curious habitations. In case of the decrease of the water, instinct

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