Plate I. fig. 1.

I have thought it more in accordance with the principles which are now almost universally adopted, in regulating specific nomenclature, to revert to the original LinnÆan name of Jason in preference to that of Fabricius. This butterfly may be regarded as one of the most splendid of the Lepidoptera of Europe, to the southern portion of which and to the northern shores of Africa it appears to be confined. The strength of its general structure indicates great powers of flight, and we accordingly find that it is able to sustain itself in the air with very little motion of the wings. The female differs from the male only by having the centre of the posterior wings adorned with small blue spots on the upper side. There are two broods in the year, namely in June and September, and, according to M. De Villiers, the insect emits a strong scent of musk. The caterpillar is naked and thickened in the middle of the body; the tail tapering into two short points, the head is also armed with two conical erect horns. In this respect, therefore, this insect very nearly approaches the genus Apatura, of which the purple Emperor, Ap. Iris is the type, thus proving the advantages to be obtained, in studying the natural relations of this difficult order of Annulosa, from an accurate acquaintance with the structure and habits of the early stages of the insect.

There are several species, having the same general form as the Jason, including Athamas, pl. 2. fig. 3. 4; Eudoxus, vol. iii. pl. 33. f. 1. 4; Camulus, vol. iii. pl. 30. f. 1. 2. Mr. Swainson has, accordingly, formed them into a distinct group, to which he has given the name of Jasia, in pursuance with his customary, but scarcely correct plan, of raising the specific name of the typical species into a generic name, and then giving a new specific name to such type. M. Boisduval, rejecting this system of nomenclature, has more recently proposed for the same group the name of Charaxes, which I have adopted.

Amongst the species very nearly resembling Jason, is one sent from Africa^[20] to Mr. Drury by Mr. Smeathman, which, according to the observations of that traveller, published by Drury, in the introduction to his third volume, flies in the heat of the day with amazing rapidity, and seldom descends within eight feet of the ground. It glances from the prominent branches of one tree to those of another, as swift as a swallow, and turns its head about instantly to the glade, or path, and will not suffer any person to approach within a striking distance of it, but darts away on the least motion of the body. If the collector exert his patience it will at last become more familiar and careless, and is then to be caught upon some particular branch, to which it will appear more attached than to another.

THECLA ACIS.

Plate I. fig. 2.

Upper Side. The anterior wings are entirely dark brown, without any spots or marks.—The posterior wings the same, with four tails, the inner ones much longer than the others; close above which latter are two red spots, edged at the bottom with black, and two more, placed at the anal angle. The cilia is white.

Under Side. All the wings are of a dark lead colour. A very narrow black and white line crosses the anterior wings, parallel to the external edges; another indented irregular line crosses the posterior wings, beginning near the middle of the anterior edge, and meeting just below the extremity of the body. Four long reddish spots are very visible on this side, below which are four black ones.