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silk-worm, the spider, and many others, is provided with a reservoir of silky matter, which is kept in store for this operation. Silk, of every kind, while in the body of the animal that produces it, is a thick viscid fluid, which the creature has power to extrude through a set of organs provided for that purpose, being small holes proportioned to the size of the thread, which acquires its form as it passes through them, as a wire does in pafsing through its mould. This fluid no sooner comes in contact with the air, than it acquires a consistency sufficient to make it preserve its continuity like a thread; but it retains, for some instants, moisture sufficient to make it adhere to such bodies as the insect chooses it should be fastened to; a single touch, while it is in this state, is sufficient to glue it, as it were, to the body to which it is to be attached, when it instantly dries, and has all the strength that the silk can ever be made to attain. The opening by which the silk of the Formica-leo is issued is at the posterior part of the abdomen at a in the figure C, where the anus of most other insects is placed, and the silk itself is so fine as to be scarcely at all perceptible with the naked eye. When it has retired to the sand for preparing its house, it begins by joining the particles of sand to each other by means of its silk, which is effected by the means of a sharp organ that it has the power to protrude from the body for that purpose; at the extremity of which the thread ifsues forth. The point of this delicate organ it applies first to one particle of sand then to another, and another all round, beginning always at the upper side, so as to form a kind of vault above, and thus it goes on, with won

derful patience and afsiduity, till it has thus joined together a large mafs of sand, which in this state is found to be adhesive, though still soft, and has then more the appearance of a congeries of loose matter kept together by a net, than any other thing to which it can be likened. The silk is not here perceptible; but on some occasions a single thread of it may be separated for a length by itself, when it appears like beads kept together by an almost imperceptible string. When the ball is thus formed of a sufficient size all round, the animal then proceeds to line this case all over with many folds of its silk laid above each other, till it acquires a palpable consistence; being clear and lustrous like the finest satin, of a bright pearly whitenefs. In this soft and close mansion the Formica-leo lies concealed for the space of several weeks, during which time, after having disengaged itself from its former skin, it appears under the form of an inactive chrysalis, with its body bent in a circular form to adapt itself to its habitation. In this state the members of the succeeding fly begin to be perceived, at first very obscurely, but gradually they acquire more and more consistence, and appear more distinetly; the abdomen is seen to be lengthened greatly in proportion to that which it bore in its larva state; in this respect differing greatly from that of caterpillars, which are usually very much contracted in length during the change it undergoes in the chrysalis state, the different members being closely laid upon the body, and surrounded, as it were, by swaddling clothes; till at length the animal, which for a long time appeared to be an

break a hole in its case and come forth, when, throwing off the slough of the chrysalis, its wings quickly extend in length, and acquire a firm consistence; and all its other members having at the same time acquired their full perfection, it mounts upon the wing, and pursues its course for the remainder of its life in the air, under the form exhibited in the plate at D, resembling that clafs of flies which, on account of the elegance of their form, have obtained the vulgar name of lady flies.

This fly, as it is destined to enjoy a longer life than that of the ephemera (though the exact duration of its existence has not, that I know, been accurately ascertained), has occasion to take sustenance while in this state, and for this purpose it is endowed with a mouth, and strong teeth for tearing its food and breaking it to pieces. It has, besides, a pair of strong pincers for seizing its prey that project beyond its mouth, and can be extended wide, or contracted, at pleasure. It probably in this state also lives upon insects as before; but it does not reject tender fruits, such as peaches and apricots. It has a pair of antennæ that are thicker towards the point than at the base. Its eyes are two, reticulated and very prominent. From the corcelet spring out four wings, arranged in a manner peculiar to this clafs of insects, which are represented as if extended when in flight. These are thin, semitransparent, of a dull whitish colour, having some dark spots as in the figure. The abdomen is long.

This fly is among the least prolific of all the insect tribe. The female is often found to contain in its body no more than one egg, which, however, is very large VOL. III.

I

in proportion to the size of the fly. From this circumstance some naturalists have imagined, that she never lays more than one egg. But the hypothesis is plainly absurd; for, as some of the larvæ must necefsarily perish before they attain perfection, and as there are males as well as females, did the female lay only one egg, the whole race must soon be totally exterminated. The fact is however, that the eggs are few, and are deposited one by one; and this breed of insects is, of course, so little numerous as to be in no danger of ever becoming either extremely destructive or troublesome.

There are several species of the Formica-Leo; one of which, found by Mr. Bonnet in the neighbourhood of Geneva, made no sand traps, and had the power of moving forward in the usual way. But the one here described is at the same time the best known, as well as the most singular in its habitudes. The others are extremely rare.

1

The fly here described is the Myrmeleon formicarium of Linnæus. Syst. Nat. page 914, n. 3.

Some of the flies of this clafs are singularly elegant and beautiful; but many of those which are called lady flies (Libellulæ) proceed from larvæ of a very different kind from the formica-leo; they form a different clafs, which we shall probably specify more particularly on some future occasion.

The male of this fly, like that of most insects, is considerably smaller than the female.

Thoughts on the origin, excellencies, and defects of the Grecian and Gothic styles of Architecture.

[Continued from Vol. II. page 434.]

On the progress of Gothic Architecture.

I AM afraid that some of my readers will be difsatisfied at being so long detained in tracing the progrefs of an almost unknown, though very enlightened society of men, which sprang up in an age of such universal darknefs, that little else has been recorded of them but their name; which has been indeed transmitted to our days, though under such clouds of obscurity as to convey no idea of its original splendour. To those, however, who wish to trace the progrefs of the human mind, and to contemplate the powers which man may attain when his energies are suffered to be steadily exerted for a sufficient length of time on one object, without experiencing the deadening effect of any restraining influence, such an investigation must be peculiarly interesting. In the hope, then, of compromising the matter between these two classes of readers, who may be supposed to be mutually inclined to yield a little to each other as occasion may call for it, I shall now proceed to lay open a few more circumstances illustrative of the attainments of the society of free-masons during those dark periods of time which we now call the middle

ages.

Long before the period which now engages our attention, considerations of great weight had induced