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Being small and elegant, they have a long and ugly scientific name, the Girardinus Guppyi. In the absence of a label, the writer mistook them for the gudgeon, which form the food of the more rapacious fishes, and was about to suggest that they would be interesting material for an experiment with the electric eels, when a ray of sunlight flashing through the bowl revealed the astonishing fact that these tiny fishes possessed beauties of ornament not exceeded in kind by any of the most exquisite birds of the tropics.

Each of the little creatures, though so frail and so delicately formed that its body offered a scarcely greater obstacle to the passage of the sunlight than the water in which it swam, was decorated on either side by one, or sometimes two, of those exquisite ornaments seen in the greatest perfection in the train of the peacock, which are perhaps best described as the “peacock-eye.” It was no mere spot, lying in a ring of a different colour, such as decorates the sides of a trout or salmon, but a perfectly-developed peacock-gem, lying in its gorgeous rings of blue, green, and gold, equally rich and dark in tint, and even more striking from its contrast with the colourless and semi-transparent body of the creature it adorned. The analogy with the pattern on the peacock’s tail was even more complete than that which a first glance disclosed; for on many of the fish a third or rudimentary eye appeared, fainter and elongated, like a smudge of wet colour, and corresponding exactly with the gradation or evolutionary process of ornament, which Charles Darwin noted in the side-feathers of the peacock-train. This wonderful decoration, which was assumed, like the brilliant red and emerald of the English sticklebacks, for the period of courtship only, disappears later in the year; and the creatures abide in plain clothes till next spring. But the character of the ornament they wear suggests a further and separate interest, beyond that which their beauty naturally claims. Pattern, by which we mean the repetition of certain and regular forms, so as to produce an ornament which pleases the eye without making any demands on the mind, is by no means a common form of natural decoration in the higher animals. Contrasts of brilliant colours, as in the plumage of the birds of paradise, and of the parrots and lorys, are the usual and beautiful adornments of birds. Any visitor to the cases of a good natural history collection, will find a hundred instances of this form of decoration for one of true pattern. Even the wings of butterflies, though spangled with colours in dots, lines, and spots, are usually devoid of pattern, though the juxtaposition of a number of the same species would instantly produce the effect of pattern. But that effect, so far as it is given in a single individual, is, as a rule, only due to the fact that the creature is itself symmetrical, and that the lines and markings on one side of the body are repeated upon the other. The stripes upon a tiger’s skin, for instance, though in the nature of ornament, are not a pattern, though a number of tigers’ skins laid side by side might produce to the eye the effect of pattern. The patterns themselves are also few in number; and these limited and favourite forms of enrichment are applied indiscriminately, and with a certain indifference to congruity of species, yet with unfailing success in the result, to the most widely-different forms in the animal creation. Take, for example, the most complex, and perhaps the most beautiful of all, natural ornaments, which appears in the “eyes” in the peacock’s tail. The same pattern, with slight variations, is found, not only on the feathers of the beautiful grouse-like Polyplectron of Malacca, though modified, as Darwin noted, by the white edging, which makes it even more conspicuous than the bronze circle round the peacock-eye, but also in the peacock-pheasant, and the Ocelated Turkey of Honduras. In this splendid bird, the “eyes” are placed in a row at the end of the tail-feathers, and upon some of the upper tail-coverts, and are rimmed with gold. The same pattern, by a leap from an order of birds not distantly connected, appears in undiminished beauty in the little fish from Trinidad; and with an almost incredible difference of subject and sameness in effect, in the peacock-butterfly and eyed hawk-moth of England, in the emperor-moth, and a number of allied insects; and lastly, with a startling resemblance, in the centre of the beautiful peacock iris, which is now cultivated in English gardens. It would, perhaps, not be difficult to add to the instances of repetition of this particular pattern which we have given, by a careful survey of the specimens exhibited in the Natural History Museum at South Kensington. But the fact of the repetition of the “peacock-eye” as ornament in the case of birds, fishes, moths, butterflies, and lastly of a common and beautiful flower, will sufficiently illustrate the fact to which we draw attention. The pattern, if less elaborate and exact in reproduction when found among the moths and butterflies, is an “impressionist” rendering of the same scheme, and if it were the reproduction of some human hand, would leave no doubt as to the identity of the motive and idea in each. The remaining natural patterns, even though of less complex form, may almost be counted on the fingers of the hand, and are applied with the same careless profusion to the adornment of creatures, like and unlike, without distinction, though the range is in most cases far more limited than in that of the peacock-eye. The most perfect form of the cup-and-ball pattern, which is seen in the feathers of the Argus pheasant, seems only to reappear on the wings of the Brahma moth, and of the eyed tortoise, though in one or two other small tortoises the effect of the ball ornament is produced by an actual embossing of the shell. Yet even in this case, not only is the form of the pattern reproduced, but also the beautiful brown colouring, which, by its soberness and exquisite gradation, produces the effect of low relief in monochrome. The wave-line, the spot, the scale-pattern, the bar-pattern, and, in rare instances, a chequer or diaper in black and white, almost exhaust the list of other natural patterns, and these, like the peacock-eye, recur in non-allied species in exactly the same arrangement, not only of form, but of colour. A most effective spot-pattern is that in which a rich chestnut ground is covered with minute white or cream-coloured spots. The result is most rich and beautiful, and it seems to be reserved for use in highly-decorated creatures of any class or family. It is seen at its best on the breast of the lovely harlequin-duck, in which the whole surface shines like enamel. But exactly the same pattern in the same colours appears on the neck of such a widely-different species as the chestnut-eared finch of Australia; and with the order of colour reversed, under the wings of the bar-breasted finch, both of which may be seen in the Parrot House at the Zoological Gardens. In the smaller wing-feathers of the Argus pheasant, this spot-pattern is reproduced on almost the same minute scale as on the harlequin-duck and the little finches. Then by a sudden change it is found on the back of the larvæ of the Gallium hawk-moth, a chestnut-coloured insect, with a row of minute white spots down the middle of its back, and two rows of rather larger white spots, one on each side. The larvæ of the spurge hawk-moth, of the white-satin moth, and of the sycamore dagger-moth, also show it. Among butterflies, the Salatura Melanippus has a border of white spots on chestnut ground round the edges of its wings; and the same arrangement may be seen on a shell—some kind of Gastropoda, if we remember rightly—which is “commonly observed” on cottage mantelpieces. The “scale-pattern” is generally due in the case of birds to the natural shape of the feathers, and not to surface-pattern. A good example is the neck of the Amherst pheasant, in which the feathers are scale-shaped, and being edged with black, produce a beautiful pattern, and the neck of the golden pheasant, in which the corresponding feathers have square ends, and the black edging merely falls into parallel lines. The perfect rectangular diaper pattern is extremely rare in birds, but not uncommon in the larvæ of moths and butterflies. It is seen in perfection on the backs of the great northern diver and its relations; and in a faint reproduction on the wings of the wood-leopard moth. A very elegant and decorative ornament is the “wave-line” pattern. This, like the chestnut ground and white spot, is constantly reproduced in the same colours, black on grey, or grey on black. It appears on the side of the wild duck, on Swinhoe’s pheasant, in which bird it is the main form of ornament, on the neck of the grass-parakeet, on the sand-grouse, on several common species of iris, and on the wings of the Brahma moths, surrounding the ball ornament to which we have referred. The inference to be drawn from these coincidences must be left to practical zoologists. But the fact that natural patterns, as applied to animals and plants, while at times showing the utmost elaboration of design, are so limited in number, and applied with so little modification in colour or form to birds, fishes, insects, and plants alike, seems an inviting subject for inquiry.