bottom on which they lay--visible to only a very sharp eye--by pitching a very small pebble right over them. Was the patch a pale one--for a minute or so they carried its pale colour along with them into some darker tract, where they remained distinctly visible from the contrast, until, gradually acquiring the deeper hue, they again became inconspicuous. But if startled back to the same pale patch from which they had set out, I have then seen them visible for a minute or so, from their over-dark tint, until, gradually losing it in turn, they paled down, as at first, to the colour of the lighter ground. An old Highlander, whose suit of tartan conformed to the general hue of the heather, was invisible at a little distance, when traversing a moor, but came full into view in crossing a green field or meadow: the suit given by nature to the flounder, tinted apparently on the same principle of concealment, exhibits a degree of adaptation to its varying circumstances, which the tartan wanted. And it is certainly curious enough to find, in one of our commonest fishes, a property which used to be regarded as one of the standing marvels of the zoology of those remote countries of which the chameleon is a native. The pond in the piece of planting, though as unsightly a little patch of water as might be, was, I found, a greatly richer study than the dark rivulet. Mean and small as it was--not larger in area inside its fringe of rushes than a fashionable drawing-room--its natural history would have formed an interesting volume; and many a half-hour have I spent beside it in the heat of the day, watching its numerous inhabitants--insect, reptilian, and vermiferous. There were two--apparently _three_--different species of libellula that used to come and deposit their eggs in it--one of the two, that large kind of dragon-fly (_Eshna grandis_), scarce smaller than one's middle-finger--which is so beautifully coloured black and yellow, as if adorned by the same taste one sees displayed in the chariots and liveries of the fashionable world. The other fly was a greatly more slender and smaller species or genus, rather _Agrion_; and it seemed two, not one, from the circumstance, that about one-half the individuals were beautifully variegated black and sky-blue, the other half black and bright crimson. But the peculiarity was merely a sexual one: as if in illustration of those fine analogies with which all nature is charged, the sexes put on the _complementary_ colours, and are mutually fascinating, not by resembling, but by _corresponding_ to, each other. I learned in time to distinguish the disagreeable-looking larvæ of these flies, both larger and smaller, with their six hairy legs, and their grotesque formidable vizors, and found that they were the very pirates of the water, as the splendid insects into which they were ultimately developed were the very tyrants of the lower air. It was strange to see