perhaps the most variable of all *. Among some hundreds which we have examined, we have seldom found two alike, even from the same nest, some being marked with large streaks and blotches, while others were so finely mottled or rather marbled, that it required minute inspection to discover the markings, as they appeared to be rather of a uniform grey. The same diversity is observable in the shades of these markings, some being of a very pale grey, and others nearly black. The eggs of the blackcap (Sylvia atricapilla) again are usually stained

Egg of Black-Cap.

rather than blotched with either a deeper or a paler flesh colour than that of the ground; but in many instances these stains are scarcely, if at all perceptible t.

We have elsewhere ‡ adverted to the fanciful notions which have been entertained respecting the final cause of the various colours in the eggs of insects, the common supposition being that they are adapted to the purposes of concealment from their natural enemies. The snake, says Dr. Darwin, the wild cat, and the leopard, are so coloured as to resemble dark leaves and their lighter interstices; and birds resemble the colour of the brown ground or the green hedges which they frequent. M. Glöger, a German naturalist, has followed up this fancy, as it respects the eggs of birds, into some detail. He considers it to be a remarkable provision of nature, that birds whose nests are most exposed, and whose eggs are most Journ, of a Nat. p. 222. † J. R. Insect Transformations, p.33.

open to the view of their enemies, lay eggs of which the colour is the least distinguishable from that of the surrounding objects, so as to deceive the eye of those animals who have a desire to destroy them; while birds, the eggs of which have a bright decided colour, and are consequently very conspicuous, either conceal their nests in hollows, or only quit their eggs during the night, or begin to sit immediately after laying. It is also, he states, to be remarked, that in the species of which the nest is open, and the female brings up the brood without the assistance of the male, the former is generally of a different colour from the latter, less conspicuous, and more in harmony with the objects around. The foresight of nature has, therefore, provided for the preservation of the species of which the nest is altogether exposed, by imparting to the eggs a colour which will not betray them at a distance; while she has been able, without inconvenience, to give the brightest colour under circumstances where the eggs are concealed from view. Or perhaps, to speak more correctly, numerous birds can deposit their eggs in places accessible to view, because the colour of the eggs enables them to be con founded with the surrounding objects; while other birds are obliged to conceal their nests, because the conspicuous colour of the eggs would have attracted their enemies. Eggs, according to the patrons of this hypothesis, must be distributed into two series according as their colour is simple or mixed. The simple colours, such as white, blue, green, yellow, are the brightest, and consequently the most dangerous for the eggs. The pure white, the most treacherous of colours, is found among birds which breed in hollow places, like the woodpecker, the wryneck, the roller, the merops, the king-fisher, the snow-bunting, the robin, the dipper, the swallow, the martin. It is only among these birds that the

The eggs

eggs are of a remarkable whiteness. are also white among some species which, like the domestic swallow, certain Passeres, the Troglodites, &c., construct their nests with such narrow openings that the eye of their enemies cannot penetrate within. White eggs are also found with birds that quit them only during the night, or, at least, very late during the day, such as the owls and falcons. Lastly, this colour is found among birds which lay only one or two eggs, and sit immediately after, like the pigeons, the boobies, and the petrels. As to the bright green or blue colour, it is found to belong to many species which make their nests in hollows, like the starling, the bullfinch, the flycatcher, &c. In the second place, this colour is common to the eggs of birds, the nests of which are constructed with green moss, or placed at least in the midst of grass, but always well concealed, such for example as the tom-tit, linnet, &c. Lastly,

Egg of the Tom-tit (Parus cæruleas).

green eggs are met with among many strong birds, such as the herons, able to defend themselves against plunderers. A light green colour, verging toward a yellowish tint, is found among the eggs of the many Gallinacea which lay among the grass, without making more than an imperfect nest, which soon disappears beneath the quantity of eggs; like the hoopoe, the Perdrix cinereus, the pheasant. The same colour is also remarked among several of the Palmipedes, which quit their eggs when they lay them, but which are attentive in watching them, as the swans, the geese, the ducks, the divers, &c. The

eggs of certain great birds which make their nests in the open air, but are well able to defend themselves, are a dirty white, as may be observed among the vultures, eagles, storks. Among the eggs of a mixed colour, those are to be distinguished which have a white ground, and those of which the ground differs from white. The eggs with a white ground are those of the European oriole, the long-tailed-tit, the cole-tit, the nut-hatch, the creeper, and the common swallow. Most of the eggs with a white ground are concealed in well-covered nests. The eggs of a mixed colour, and of which the ground is not white, at least a pure white, are those of the lark, the grass-hopper bird (Curruca locustella,

FLEMING), the yellow-hammer, the wagtail, &c.; then those of the crows, the jays, the thrushes, the quails, &c., with most of the singing birds, the colour of the interior of whose nest harmonizes with that of the eggs *.

Such is the theory; and M. Glöger, after examining all the birds of Germany, is said to have proved that the facts universally correspond to it. In conformity with the same notion, Dr. Darwin remarks that the eggs of the hedge-sparrow (Accentor modularis) are greenish blue, like those of magpies and crows, which are seen from beneath in wicker nests, between the eye and the blue of the firmament; but he forgets that the eggs of the songthrush, which are no less bright blue than those of *Verhand. der Gesellschaft Nat. Freunde, in Berlin.

tecting the eggs or young from the bleak winds which prevail in the early part of the spring, when the songthrush breeds.

Nest of the Song-thrush (Turdus musicus).

The song-thrush usually builds in a thick bush, hawthorn, holly, silver-fir, furze, ivied tree, or sometimes in a dead fence, where the grass grows high; but it has occasionally been known to nestle within out-buildings. We saw one, during the spring of 1829, in a garden summer-house at Southend, Lewisham; and another is mentioned in the Magazine of Natural History, as having been built upon a harrow. A mill-wright" had been making a threshing-machine for a farmer in the neighbour