sixth problems; then the respective areas being collected into one sum, it will be the content required.

Example: Required the content of a field having five sides from the following dimensions.

Son. What is the difference between a trapezoid and a trapezium?

Mr. B. A trapezoid is a plane four-sided figure, having two of the opposite sides parallel to each other. A trapezium is a plane figure contained under four unequal right lines, none of them parallel.

Another method of surveying a piece of ground having more than four sides is, by measuring a base line either within or without it, and also the perpendiculars let fall upon that line from every angle of the field. By this means it is divided into right-angled triangles and trapezoids, the areas of which being properly collected, will be the content required.

Entomology.

Mr. B. The next genus after the Coccinella described in our last lesson is the different species of the beautiful race of

insects called Chrysomela, which feed on the pulp of the leaves of the willow, poplar, and birch trees, but neglect the fibres. That which is found on the poplar is twice the size of a common lady-bird, and is bright red, with the tips of the wing-shells black, and a bluish hue on the underpart: the larva is of a pale yellowish green speckled with black, and edged with rows of bristles, which, when the insect is handled, emit a disagreeable odour, by means of a white fluid that issues from a pore at the top of each of them. Another species of this genus is described by Linnæus under the name of Chrysomela Asparagi, but it is now called Crioceris Asparagi; it is of a deep blue-green colour, and very shining. The larvæ, beetles, and eggs are found at the same periods, often inhabiting the same plant, from Midsummer to Michaelmas; the former feed upon the leaves and flowering stems, which they completely destroy. The larvæ are shining, fleshy, and of a dirty olive-green or slate colour. When arrived at maturity, which requires only a fortnight, they leave the plant and descend into the earth to undergo undergo their transformations, they first spin a case or cocoon which is tough and parchment-like, and within this they change to a white pupa, which lies in a curved position. In two or three weeks the perfect beetle emerges from its cell, and ascends the asparagus plants to reproduce its species.

Journeyman. I recollect that a few years ago in July the seedling plantations of asparagus at Grayson's market-garden, Mortlake, and other places in the neighbourhood of London, were severely injured by some species of insect which I now understand must have been the Asparagus beetle. Picking was resorted to, but I think they were shaken into nets as the more speedy method of destroying them.

Mr. B. The next genus Hispa, is rare and singular in its appearance, bearing some resemblance to a hedgehog in miniature; it being a small black insect, thickly beset with spines, you must look for it at the roots of grass.

The genus Bruchus is found upon pea-blossoms; its colour is black, speckled with white, the two fore-legs are reddish, and the hind-legs are armed with a sort of tooth, the purpose of which does not seem to be known.

I must now introduce the genus Curculio or weevil to your notice; a very numerous and destructive tribe. One of them is very familiar, though, I suppose, its habits are unknown to you. The next bunch of nuts that fall in your way, examine each closely, and if there are any small holes in the shells you may depend upon it, the larva of the nut-weevil has been at work. The perfect insect, early in August, hovers about nut trees, for the purpose of providing a secure retreat for

her future progeny. Directed by pure instinct, for it cannot be affection for objects she has never seen, she singles out a nut, which she pierces with her proboscis, and then, turning round, deposits an egg in the hole she has bored. She passes from one nut to another, providing in the same manner for her whole stock of eggs. The nut, apparently uninjured, continues to grow till the kernel is ripe. When the maggot is hatched it feeds on the nut; which, by the time it is nearly consumed, falls to the ground, without hurting its inmate. When approaching its change, the maggot prepares for its escape by enlarging the hole previously made in the shell. As soon as it has emerged from its lurking place, it begins to burrow under the surface of the ground, where it lies dormant for eight months, and then, casting its skin, becomes a chrysalis; in which state it remains till August, when it assumes the form of a small, brown beetle, with a very long snout. In a manner similar to that I have just described, another species of the same genus attacks the grains of corn, and produces very serious mischief.

Curculio lineatis (the striped pea-weevil) is another species of the same family which is exceedingly injurious to young peas. In a season favourable for these beetles they have been known to make their appearance in thousands about the end of March, and for a fortnight have caused very extensive mischief to the peas; in some instances entirely eating off the second and third sowing, when the young plants had grown three or four inches above the surface. At that early period of the year they have been observed to come out of the earth about nine or ten o'clock in the morning, and after feeding all day, to retire into the loose ground again as evening approached.

Curculio abietis (the spruce-fir weevil) is another beetle of the same genus. Although it was thus named by Linnæus its ravages are not confined to that tree, for it equally attacks the scotch fir and larch, and it has been also observed on rhododendrons, azaleas, and alders, which it will feed upon. The spruce-fir weevils, however, generally fix on those pines which have been recently planted, or such as are sickly, in which the sap circulates sluggishly, and it is thus that the young larch plantations have been suffering severely of late years from their attacks. Instances have been known where they have stripped every young tree of its bark up to the summit, while older trees in the same plantation were left untouched. It is supposed, but has not been proved, that the females deposit their eggs deep in the roots of the trees in July and August, and that the beetles hybernate in the loose soil. The galleries formed by the young larvæ can be

traced upwards from the roots, and Bouché says they perforate the young shoots and live in the wood. They are fleshy-white maggots, like those of most Curculionidæ, with a brown head. We have no description of the pupa, or any account where it undergoes its transformations. Handpicking is recommended as the easiest and most efficient mode of destroying them. There is a great similarity between many of the succeeding genus Attelabus, in both the perfect and larva states, and the Cuculio that I have just described. In their habits they are also much alike.

The next genus Cerambyx, or capricorn, is very extensive, containing many insects of the most extraordinary appearance, and exceeding in size any in the order Coleoptera, except genus Scarabæus.

The Cerambyx longimanus measures nearly three inches in length: the wing-shells are covered with a very fine down, and are beautifully varied with red, black, and yellow stripes; the forelegs are very long, and barred with red.

The Goat-chafer, or musk beetle is one of this genus, and takes its name from its powerful scent, resembling that of musk, ambergris, and roses. You may find it on the willow.

The genus Leptura bears great resemblance to that of Cerambyx, especially the larva, both in habits and appearance. Some of them are very beautiful.

The Leptura arcuata is black, marked on the wing-sheath with bright yellow semicircular bands. Some of the Leptura are found in Kent, in the bean and pea fields, on currant bushes and on fern.

The genus Necydalis, carrion-eater, is distinguished from the other insects of the first order in having the wings extended their whole length, instead of being folded under the elytra.

Necydalis cærulea is an elegant species; it is not more than half an inch in length, and its colour is a light blue, sometimes inclining to green. It is found in woods during the summer months.

Who has not in his youth beheld, with astonishment and delight, the beautiful light of the Lampyris noctiluca, or common glow-worm? Every man who takes an interest in contemplating the pleasant and peaceful ways of Nature, must look with admiration on these little animals, sparkling on a bank, or scattered like living gems amongst the brushwood. Brilliant as this insect (which is the female) appears in the darkness of night, when examined by daylight it is a little creature about three quarters of an inch long, of a dull earthy brown on the back, the under part tinged with rosecolour; the two or three last joints of the body are of a pale

sulphur, from whence the phosphoric light proceeds. The larva, pupa, and complete female insect, in their general appearance differ but little from each other; but the luminous brightness is most striking in the last state, and is displayed or withheld at pleasure, being increased by the motion of the insect, and diminished or obscured by either unfolding or contracting the body. This curious property is given to the female glow-worm, which is destitute of wings, as a means of attracting the notice of the male, which is a flying insect, and without this dazzling invitation would be at a loss to discover his mate in the dark. The glow-worms lie in the most profound repose during the day, and only become active on the approach of night. The males may be captured by placing a female glow-worm in the hand at night.

The genus Cantharis comprises a number of small insects, adorned with gay colours, depending greatly on sex, seasons, &c., so that a description of one of them will suffice. The Cantharis bipustulata is of a slender shape, and of a very dark but elegant gilded green, with the tips of the wingshells red; on each side of the thorax, a little below the setting on of the wing-shells, lies a triple vessel, or bladder, which the insect can extend or draw in as it pleases. From inspecting this appendage with the microscope, an alternate inflation and contraction is perceptible, like the motion of the lungs in the larger animals, and probably is applicable to the same purpose. This insect frequents various plants, particularly the nettle. Most of the tribe are very voracious—some of them have been seen to prey on their own species.

Of the various species of wireworms that inhabit this country there are only three or four whose larvæ do much mischief; they are the Elater spectator, E. obscurus, E. lineatus, and E. ruficaulis. Their economy is similar; and as the Elater lineatus has been most frequently reared, its history is best known. The beetles are found in fields and gardens, woods and hedges, from April to July; the females are supposed to lay their oval whitish eggs in the earth, close to the plant which is to supply nourishment to the future progeny, and as soon as the larvæ are hatched they commence eating into the stem or root, and frequently consume the centre of the stalk even above the surface of the ground. They are at first very small, but are generally three-quarters of an inch long when full grown, and it is asserted that they are five years in undergoing their transformations. When they have done feeding and have cast off three skins during their increase in size, they form an oval cell at some distance in the earth, when they change about July and Agust to pupæ. After re