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moth varies itself in colour; in one of the varieties it has a central black band across the wings, when it resembles Calopteron vicinum (Deyrolle), in another this black band is wanting, when it resembles C.basalis. Professor Westwood has also pointed out to me that the resemblance to the beetle is still further increased in the moth by raised lines of scales running lengthwise down the thorax.
The phosphorescent species of Lampyridæ, the fireflies, so numerous in tropical America, are equally distasteful, and are also much mimicked by other insects. I found different species of cockroaches so much like them in shape and colour that they could not be distinguished without examination. These cockroaches, instead of hiding in crevices and under logs like their brethren, rest during the day exposed on the surface of leaves, in the same manner as the fireflies they mimic.
Protective resemblances amongst insects are so numerous and wide-spread, and they have been so ably described by Bates and Wallace, that I shall only mention a few of the most noticeable examples that came under my attention, and which have not been described by other authors. Amongst these were the striking modifications of some beetles belonging to the Mordellidæ. These, in their normal form, are curious wedge-shaped beetles, which are common on flowers, and leap like fleas. In some of the Nicaraguan species the body is lengthened, and the thorax and elytra coloured, so as to resemble wasps and flies. In the Mordellidæ the head is small, and nearly concealed beneath the large thorax; and in the mimetic forms the latter is coloured so as to resemble the large head and eyes of the wasp or fly imitated. The species that
resembles a wasp moves its antennæ restlessly, like the latter insect.
The movements, as well as the shape and colour of the insect imitated, are mimicked. I one day observed what appeared to be a hornet, with brown semi-transparent wings and yellow antennæ. It ran along the ground vibrating its wings and antennæ exactly like a
hornet, and I caught it in my net, believing it to be one. On examining it, however, I found it to belong to a widely different order. It was one of the Hemiptera, Spiniger luteicornis (Walk.), and had every part coloured like the hornet (Priocnemis) that it resembled. In its vibrating, coloured wing-cases it departed greatly from the normal character of the Hemiptera, and assumed that of the hornets.
All the insects that have special means of protection, by which they are guarded from the attacks of insectivorous mammals and birds, have peculiar forms, or strongly contrasted, conspicuous colours, and often make odd movements that attract attention to them. There is no attempt at concealment, but, on the contrary, they appear to endeavour to make their presence known. The long narrow wings of the Heliconii butterflies, banded with black, yellow, and red, distinguish them from all others, excepting the mimetic species. The banded bodies of many wasps, or the rich metallic colours of others, and their constant jerky motions, make them very conspicuous. Bees announce their presence by a noisy humming. The beetles of the genus Calopteron have their wing-cases curiously distended, and move them up and down, so as to attract attention; and other species of Lampyridæ are phosphorescent, holding out danger signals that they are not eatable. The reason in all these cases appears to be the same as Mr. Wallace has shown to hold good with banded, hairy, and brightly coloured caterpillars. These are distasteful to birds, and, in consequence of their conspicuous colours, are easily known and avoided. If they were like other caterpillars, they might be seized and injured before it was known they were not fit for food.*
Amongst the mammals, I think the skunk is an example of the same kind. Its white tail, laid back on its black body, makes it very conspicuous in the dusk
* In a paper on “Mimicry, and other Protective Resemblances amongst Animals,” first published in the Westminster Review, July 1867, afterwards in “ Natural Selection," Wallace has elaborately discussed this question. My observations are supplemental to his and to the original ones of Bates.
when it roams about, so that it is not likely to be pounced upon by any of the carnivora mistaking it for other night-roaming animals. In reptiles, the beautifully banded coral snake (Elaps), whose bite is deadly, is marked as conspicuously as any noxious caterpillar with bright bands of black, yellow, and red. I only met with one other example amongst the vertebrata, and it was also a reptile. In the woods around Santo Domingo there are many frogs. Some are green or brown, and imitate green or dead leaves, and live amongst foliage. Others are dull earth-coloured, and hide in holes and under logs. All these come out only at night to feed, and they are all preyed upon by snakes and birds. In contrast with these obscurely coloured species, another little frog hops about in the daytime dressed in a bright livery of red and blue. He cannot be mistaken for any other, and his flaming vest and blue stockings show that he does not court concealment. He is very abundant in the damp woods, and I was convinced he was uneatable so soon as I made his acquaintance and saw the happy sense of security with which he hopped about. I took a few specimens home with me, and tried my fowls and ducks with them, but none would touch them. At last, by throwing down pieces of meat, for which there was a great competition amongst them, I managed to entice a young duck into snatching up one of the little frogs. Instead of swallowing it, however, it instantly threw it out of its mouth, and went about jerking its head as if trying to throw off some unpleasant taste.*
* Probably the strongly contrasted colours of the spotted salamander of Southern Europe and the warning noise made by the rattlesnake may be useful in a similar manner, as has been suggested by Darwin.
After travelling three leagues beyond Teustepe, we reached, near dusk, a small house by the roadside, at which had put up for the night a party of muleteers, with their mules and cargoes. Our beasts were too tired to go further, so we determined to take our chance of finding room for our hammocks. Soon after we alighted, as I sat on a stone near the door of the house, a gun went off close to us, and my horse sprang forward, nearly upon me. We soon found it was our own gun, which had been given to Rito to carry. He had strapped it behind his saddle, and one of the other mules had come up, rubbed against it, and let it off. The poor horse was only four feet from the muzzle, and the contents were lodged in its loin. A large wound was made from which the blood flowed in a great stream, until Velasquez got some burnt cloth and stanched it. Fortunately the charge in the gun was a very light one, and no vital part was touched. We arranged with the muleteers to take our cargo to Juigalpa for us, and determined to leave Rito behind to lead the horse gently to Pital. The horse, which was a very good one, ultimately recovered.
At this house the woman had eight children, the eldest, I think, not more than twelve years of age. The man who passed as her husband was the father of the youngest only. Amongst the lower classes of Nicaragua men and women often change their mates. In such cases the children remain with the mother, and take their surname from her. Baptism is considered an indispensable rite, but the marriage ceremony is often dispensed with ; and I did not notice that those who lived together without it suffered in the estimation of