_Upper Side._ The antennæ are dark brown, at the tips paler; and terminating in a point. The head, thorax, and base of the abdomen dark chocolate brown; the extremity and sides of the latter dark. Anterior wings of a fine deep chocolate brown. A narrow, irregular, and oblique cream-coloured bar runs across the wing; between this and the tip, from the anterior edge, runs another crooked irregular bar, of a much darker colour, reaching almost half across the wing towards the interior angle, the external margin being of a lighter shade. Posterior wings, having a white bar running transversely across the wing, widening by degrees, and ending at the anal angle. Six square orange spots also of different sizes, are placed within the external margin of these wings. _Under Side._ Anterior wings, in the middle, dark chocolate; the tips dark fawn colour, lighter next the shoulders. The two irregular bars, on the upper side, are here a little broader. Within the external edge are three rather pearly white spots. Posterior wings greyish fawn colour, with the {30}external edges darker. A pale pearl-coloured bar runs across the wing beyond the middle, widening gradually; below this are some very faint brown spots, and near the external edge some faint orange ones, scarcely visible. The edges of all the wings are entire. The genus Castnia is another of those curious anomalous forms, which exhibit the characters of several groups. The general form of the wings is that of a moth, whilst the variegated colours, indicating diurnal flight, and the structure of the antennæ are those of a butterfly. It is much to be regretted, that travellers in South America have not ascertained the preparatory states of this extraordinary group, which alone will enable us satisfactorily to ascertain its real relations. GASTROPACHA? OTUS. Plate XVI. fig. 3. ORDER: Lepidoptera. SECTION: Nocturna. FAMILY: Bombycidæ, _Steph._ GENUS. GASTROPACHA? _Ochsenh._ Sphinx, _Drury_. GASTROPACHA? OTUS. Alis elongatis integris luteo-fuscis, anticis fasciis duabus denticulatis nigris. (Expans. Alar. 4 unc. 6 lin.) SYN. Sphinx Otus. _Drury, Append. v._ 2. Bombyx Agrius, _Oliv. Enc. Méth._ 5. 39. 56. HABITAT: Smyrna (_Drury_).