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Genus ORNITHOPTERA.
The present generic group was first separated from Papilio by Dr. Boisduval. None of its characters, taken singly, are very strongly marked, but their aggregate importance is sufficiently considerable to authorise its adoption. As in Papilio the antennæ form an elongate club, having the extremity slightly curved upwards, the palpi are longer than in the genus just named, but they never rise above the forehead. The prothorax is much developed anteriorly, and forms a pretty distinct neck. The abdomen is long and robust, that of the male deeply grooved on the under side, and provided at the anal extremity with two large rounded valves. The wings are large, of a strong texture, and furnished with salient nervures; the anterior pair elongate; the posterior with wide shallow indentations, and never prolonged into a tail.
We are very imperfectly acquainted with the natural history of the insects of this group in their early stages. Their remote localities, and the rarity of most of the species, have, for the most part, prevented them from falling under the notice of competent observers. The caterpillar and metamorphoses of one of them (O. Heliacon), however, have been described by Dr. Horsfield. Like the
