[15] In consequence of the great increase of the science it has been found necessary to divide the Orders of Insects into Sections, Families, Subfamilies, &c. before arriving at Genera, which are now much more limited than in the time of Linnæus. [16] There is no branch of natural history where the existence of a _Lusus Naturæ_ is so plain and observable as in this, particularly among the insects brought from warm climates; where the wantonness and luxuriance of nature is so great; that its laws, strict and regular as they are, through the rest of the animal creation, almost seem to be invaded and broke in upon. Instances, also, are frequent in this study, of a cluster of eggs being discharged by a female, the insects springing from which, have differed in the circumstances above-mentioned so very greatly, as in some cases to be mistaken for different species. [17] In these definitions, I have thought it serviceable to give the modern names without introducing those, now out of use, employed by Drury, &c. The most conspicuous parts are alone noticed. (_J. O. W._) [18] By five eyes, I mean those that have three lesser ones, as in Plate 43, 44, 45, &c. See the Plate in the Preface, fig. 4. [19] They are part of and give support to the hind pair of legs. [20] 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." [21] 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.