more durable edifices than those which have fallen under our observation;-for Réaumur says they were harder than many sorts of stone, and could scarcely be penetrated with a knife. Ours, on the contrary, do not seem harder than a piece of sunbaked clay, and by no means so hard as brick. One circumstance appeared inexplicable to Réaumur and his friend Du Hamel, who studied the operations of these insects in concert. After taking a portion of sand from one part of the garden-walk, the bees usually took another portion from a spot almost twenty and sometimes a hundred paces off, though the sand, so far as could be judged by close examination, was precisely the same in the two places. We should be disposed to refer this more to the restless character of the insect, than to any difference in the sand. We have observed a wasp paring the outside of a plank, for materials to form its nest; and though the plank was as uniform in the .qualities of its surface, nay, probably more so than the sand could be, the wasp fidgeted about, nibbling a fibre from one, and a fibre from another portion, till enough was procured for one load. In the same way, the whole tribe of wasps and bees flit restlessly from flower to flower, not unfrequently revisiting the same blossom, again and again, within a few seconds. It appears to us, indeed, to be far from improbable, that this very restlessness and irritability may be one of the springs of their unceasing industry.

By observing, with some care, the bees which we found digging the clay, we discovered one of them (Osmia bicornis) at work upon a nest, about a gunshot from the bank. The place it had chosen was the inner wall of a coal-house, facing the south-west, the brick-work of which was but roughly finished. In an upright interstice of half an inch in width, between two of the bricks, we found the little architect

assiduously building its walls.. The bricklayer's mortar had either partly fallen out, or been removed by the bee, who had commenced building at the lower end, and did not build downwards, as the social-wasps construct their cells.

The very different behaviour of the insect here, and at the quarry, struck us as not a little remarkable. When digging and preparing the clay, our approach, however near, produced no alarm; the work went on as if we had been at a distance; and though we were standing close to the hole, this did not scare away any of the bees upon their arrival to procure a fresh load. But if we stood near the nest, or even in the way by which the bee flew to it, she turned back or made a wide circuit immediately, as if afraid to betray the site of her domicile. We even observed her turning back, when we were so distant that it could not reasonably be supposed she was jealous of us; but probably she had detected some prowling insect-depredator, tracking her flight with designs upon her provision for her future progeny. imagined we could perceive not a little art in her jealous caution, for she would alight on the tiles as if to rest herself; and even when she had entered the coal-house, she did not go directly to her nest, but again rested on a shelf, and at other times pretended to examine several crevices in the wall, at some distance from the nest. But when there was nothing to alarm her, she flew directly to the spot, and began eagerly to add to the building.

We

It is in instances such as these, which exhibit the adaptation of instinct to circumstances, that our reason finds the greatest difficulty in explaining the governing principle of the minds of the inferior animals. The mason-bee makes her nest by an invariable rule; the model is in her mind, as it has been in the mind of her race from their first creation: they

have learnt nothing by experience. But the mode in which they accomplish this task varies according to the situations in which they are placed. They appear to have a glimmering of reason, employed as an accessary and instrument of their instinct.

The structure, when finished, consisted of a wall of clay supported by two contiguous bricks, enclosing six chambers, within which a mass of pollen, rather larger than a cherry-stone, was deposited, together with an egg, from which in due time a grub was hatched. Contrary to what has been recorded by preceding naturalists, with respect to other mason-bees, we found the cells in this instance quite parallel and perpendicular; but it may also be remarked, that the

Cells of Mason-Bees, built, in the first and second figures, by Osmia bicornis between bricks, and in the third, by Megachile muraria in the fluting of an old pilaster; about half the natural

size.

bee itself was a species altogether different from the one which we have described above as the Anthophora retusa, and agreed with the figure of the one we caught quarrying the clay-(Osmia bicornis).

There was one circumstance attending the proceedings of this mason-bee which struck us not a little, though we could not explain it to our Own

satisfaction. Every time she left her nest for the pur- i pose of procuring a fresh supply of materials, she paid a regular visit to the blossoms of a lilac tree which grew near. Had these blossoms afforded a supply of pollen, with which she could have replenished her cells, we could have easily understood her design; but the pollen of the lilac is not suitable for this purpose, and that she had never used it was proved by all the pollen in the cells being yellow, whereas that of the lilac is of the same pale, purple colour as the flowers. Besides, she did not return immediately from the lilac tree to the building, but always went for a load of clay. There seemed to us, therefore, to be only two ways to explain the circumstance: she must either have applied to the lilac blossoms to obtain a refreshment of honey, or to procure glutinous materials to mix with the clay.

When employed upon the building itself, the bee exhibited the restless disposition peculiar to most hymenopterous* insects; for she did not go on with one particular portion of her wall, but ran about from place to place every time she came to work. At first, when we saw her running from the bottom to the top of her building, we naturally imagined that she went up for some of the bricklayer's mortar to mix with her own materials; but upon minutely examining the walls afterwards, no lime could be discovered in their structure, similar to that which was apparent in the nest found in the wall of Greenwich Park.

Réaumur mentions another sort of mason-bee, which selects a small cavity in a stone, in which she forms her nest of garden mould moistened with gluten, and afterwards closes the hole with the same material.

The fifth order of Linnæus; insects with four transparent veined wings.

A very small sort of bees (Andrena), many of them not larger than a house-fly, dig in the ground tubular galleries little wider than the diameter of their own bodies. Samouelle says, that all of them seem to prefer a southern aspect; but we have found them in banks facing the east, and even the north. Immediately above the spot where we have described the mason-bees quarrying the clay, we observed several holes, about the diameter of the stalk of a tobacco-pipe, into which those little bees were seen passing. The clay here was very hard; and on passing a straw into the hole as a director, and digging down for six or eight inches, a very smooth circular gallery was found, terminating in a thimble-shaped horizontal chamber, almost at right angles to the entrance, and nearly twice as wide. In this chamber