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ranges and with a good natural drainage is much more unhealthy, fevers being very prevalent. As at Greytown so at Pernambuco, the trade winds blow with much regularity, and there are no hills nor hollows to interfere with the movements of the air, so that miasmatic exhalations cannot accumulate. Surrounding the cleared portions around Greytown is a scrubby bush, amongst which are many guayava trees (Psidium sp.) having a fruit like a small apple filled with seeds, of a sub-acid flavour, from which the celebrated guava jelly is made. The fruit itself often occasions severe fits of indigestion, and many of the natives will not swallow the Small seeds, but only the pulpy portion, which is said to be harmless. I saw another fruit growing here, a yellow berry about the size of a cherry, called “Nancito” by the natives. It is often preserved by them with spirit and eaten like olives. Beyond the brushwood, which grows where the original forest has been cut down, there are large trees covered with numerous epiphytes—Tillandsias, orchids, ferns, and a hundred others, that make every big tree an aérial botanical garden. Great arums are perched on the forks and send down roots like cords to the ground, whilst lianas run from tree to tree or hang in loops and folds like the disordered tackle of a ship. Green parrots fly over in screaming flocks, or nestle in loving couples amidst the foliage; toucans hop along the branches, turning their long, highly-coloured beaks. from side to side with an old-fashioned look, and beautiful tanagers (Ramphocaelus passerinii) frequent the outskirts. of the forest, all velvety black, excepting a large patch of fiery-red above the tail, which renders the bird very


conspicuous. It is only the male that is thus coloured, the female being clothed in a sober suit of greenishbrown. I think this bird is polygamous, for several of the brown ones were always seen with one of the redand-black ones. The bright colours of the male must make it very conspicuous to birds of prey, and, probably in consequence, it is not nearly so bold as the obscurelycoloured females. When a clear space in the brushwood is to be crossed, such as a road, two or three of the females will fly across first, before the male will venture to do so; and he is always more careful to get himself concealed amongst the foliage than his mates. I walked some distance into the forest along swampy paths cut by charcoal burners, and saw many beautiful and curious insects. Amongst the numerous butterflies, large blue Morphos and narrow, weak-winged Heliconidae, striped and spotted with yellow, red, and black, were the most conspicuous and most characteristic of tropical America. Amongst the beetles I found a curious longicorn (Desmiphora fasciculata), covered with long brown and black hairs, and closely resembling some of the short, thick, hairy caterpillars that are common on the bushes. Other closely allied species hide under fallen branches and logs, but this one clung exposed amongst the leaves, its antennae concealed against its body, and its resemblance to a caterpillar so great, that I was myself at first deceived by it. It is well known that insectivorous birds will not touch a hairy caterpillar, and this is only one of numberless instances where insects, that have some special protection against their enemies, are closely imitated by others belonging to different genera, and even different orders. Thus, wasps and stinging ants have hosts of imitators amongst moths, beetles, and bugs, and I shall have many curious facts to relate concerning these mimetic resemblances. To those not acquainted with Mr. Bates's admirable remarks on mimetic forms, I must explain that it is only on account of the poverty of our language that we have to speak of one species imitating another, as if it were a conscious act. No such idea is entertained, and it might have been well if some new term had been adopted to express what is meant. These deceptive resemblances are supposed, by the advocates of the origin of species by natural selection, to have been brought about by varieties of one species, that somewhat resembled another having special means of protection, being preserved from their enemies in consequence of that unconscious imitation. The resemblance, which was perhaps at first only remote, is supposed to have been increased in the course of ages by the varieties, that more and more closely approached the species imitated, in form, colour, and movements, being protected. These resemblances are not only between insects of different genera and orders, but between insects and flowers, leaves, twigs, and bark of trees, and between insects and inanimate nature. They serve often for concealment, as when leaves are imitated by leaf-insects and many butterflies; or for a disguise that enables predatory species to get within reach of their prey, as in those spiders that resemble the petals of flowers amongst which they hide. That I may not travel over the same ground twice, I may here mention that on a subsequent visit to Greytown Mr. Hollenbeck lent me his horse, and I rode a few miles northward along the beach. On my return, I tied up the horse and walked about a mile over the

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