They are part of and give support to the hind pair of legs.
The name of this African species has not been recorded. The following additional observations by Mr. Smeathman will be serviceable in enabling us to obtain an idea of the treasures which, even yet, European entomologists may expect to receive from this but little investigated quarter of the globe. "The whole country of Africa, within the tropics, is one immense forest, except where the sandy plains are too unsettled to afford a proper footing for vegetation. Wherever any inhabitants settle, they make plantations by cutting down the woods and burning them to fertilize the ground, and never sow two years together on the same spot, but let the trees grow up again for two or three years, by way of fallow, before they attempt to get another crop from it. It is these spots, which Smeathman calls recent plantations, which afford the greatest variety of insects and the easiest obtained. In the second and third year they become impassable to human feet."
Sir J. E. Smith states that the Linnæan cabinet does not contain a specimen of this insect, nor of the Ilioneus of "the Insects of Georgia," pl. 2, one of the figures of which was considered by Mr. Jones, the celebrated lepidopterist, to be the Linnæan Troilus. Nevertheless, on the authority of the Banksian cabinet labelled (from recollection alone) by Fabricius, Sir J. E. Smith gave the Asterias under the name of Troilus, and the true Troilus as a new species.
From the peculiar power of contraction and elongation possessed by these segments, and which is found in the caterpillars of other species of Deilephila, these insects have obtained the name of Elephant-hawk Moths.
Since this was written, I have been favoured by Mr. MacLeay with an inspection of his magnificent collection, which possesses a Goliathus, nearly resembling the insect here figured, and which that gentleman considers as a variety of this. It is, however, considerably smaller, and the horns of the head are not so much developed.