Often through the woods a loud, sharp, resonant stridulation is heard, sounding like the syllables "Ta, na, na," succeeding each other with little intermission. It is produced by a species of wood cricket, called by the natives after the sound it produces. The total length of the body is two inches and a quarter when the wings are closed. The insect has an inflated bladder-like shape, owing to the great convexity of the thin, firm, parchmenty wing-cases; the little creature being of a pale green colour. The instrument by which it produces its music is contrived out of the ordinary nervures of the wing-case. In each wing-case the under edge of the wing itself has a horny lobe. On one wing this lobe has a sharp raised margin, on the other the strong membrane which traverses it on the under side is crossed by a number of fine and sharp furrows like those of a file. When the insect rapidly moves its wings, the file of the one lobe is scraped sharply across the horny margin of the other, thus producing the sounds; the parchmenty wing-cases and the hollow drum-like space they enclose assisting to give resonance to the tones. These notes are the call notes of the males, inviting a mate to his burrow. [Bates.] WOOD BEETLES. Enormous as are the trees of the Amazonian forests, and able to withstand the fiercest storms, they have frequently to succumb to the attacks of minute insects. Many a monarch of the woods has been brought low by the efforts of the persevering termites; but they have other enemies. The palm-trees are assailed by a group of beetles (the Histeridae) which take possession of the moist interior of their stems. One of these is an enormous fellow--the hister maximus. Another group have their bodies as thin as wafers, to enable them to live in the narrow crevices of the bark. One set of species, however (the trypanaeus), are totally different, being cylindrical in shape. They drill holes in the solid wood, and look like tiny animated gimlets when seen at work; their pointed heads being fixed in the wood, while their smooth glossy bodies work rapidly round so as to create little streams of sawdust from the holes. The caribi, which in Europe perform the important duty of scavengers, and live on the ground, are in South America nearly always found on trees. Some are of enormous size. The Hercules beetle, which lives on the mamma Americana, attains a length of five and sometimes six inches. It is known by the singular horn-shaped proboscis rising from the head and thorax, which gives it so formidable an appearance. Its duty is probably to eat up the rotten wood. Other members of the family,--known as the elephant, Neptune, and typhon,--excavate burrows in the earth, living on the decomposed trunks of trees during the day, and flying about at night with a loud humming noise--apparently to enjoy the air, of which they are deprived in the daytime.