Page:The naturalist on the River Amazons 1863 v1.djvu/326

 great Æschnæ dragon-flies, take their insect prey whilst on the wing, when the upper surface of the wings is the side most conspicuous.

In the broad alleys of the forest where these beautiful insects are found, several species of Morpho were common. One of these is a sister form to the Morpho Hecuba, which I have mentioned as occurring at Obydos. The Villa Nova kind differs from Hecuba sufficiently to be considered a distinct species, and has been described under the name of M. Cisseis; but it is clearly only a local variety of it, the range of the two being limited by the barrier of the broad Amazons. It is a grand sight to see these colossal butterflies by twos and threes floating at a great height in the still air of a tropical morning. They flap their wings only at long intervals, for I have noticed them to sail a very considerable distance without a stroke. Their wing-muscles and the thorax to which they are attached, are very feeble in comparison with the wide extent and weight of the wings: but the large expanse of these members doubtless assists the insects in maintaining their aërial course. Morphos are amongst the most conspicuous of the insect denizens of Tropical American forests, and the broad glades of the Villa Nova woods seemed especially suited to them, for I noticed here six species. The largest specimens of Morpho Cisseis measure seven inches and a half in expanse. Another smaller kind, which I could not capture, was of a pale silvery-blue colour, and the polished surface of its wings flashed like a silver speculum, as the insect flapped its wings at a great elevation in the sunlight.