Early in the summer they spin a glossy silken cocoon, generally attached to blades of grass, and remain but a few days in the pupa state. A great proportion of the perfect insects have hyaline spots and patches in their wings, and nearly all of them are brilliantly coloured. It is known that Linnæus occasionally, as in Tenebrio and the present instance, made his genera recipients of species, which he found a difficulty in locating properly; but it is really astonishing to find a naturalist like Latreille abiding by so absurd a combination as the contents of the Linnæan genus Sphinx, and, in servile imitation, calling creatures which nothing but an unclouded sun ever tempts abroad--Crepuscularia.[37] It is no part of my present plan to assign names to orders, or to describe their contents, except in those particular instances in which the more immediate object of this Essay may render it imperative. I will, however, just observe, that I by no means consider Zygæna the type of the order, but merely the nearest point of contact with Sphinx, and an evident departure from its true type, which perhaps may be found in that ill-divided genus Glaucopis, the form and appearance of which is altogether more Pyralis-like than Zygæna. I am well aware that OEgocera and Zygæna do not harmonize so beautifully as many other approaches, and fully expect to see the connexion between these sub-classes much improved; but I have seized on these genera as demonstrating a tendency in each individual towards the sub-class to which it does not belong. The circumstance of Zygæna having been so long considered a Sphinx will warrant its situation on the very circumference of the circle which contains its order, until a more appropriate occupant of that situation can be found. At the central point of contact, the genus Aglossa presents a very Bombyx-like appearance; its shape, its want of the antlia, &c. indicate approach; and from the sub-class Tinea, the division of Pyralis is at present an imaginary one: at this point, after making what little comparison I am able, I am induced to place Galleria, Melia, and Ilithya, in Pyralis; and Chilo, and Crambus in Tinea. [37] Volatu vespertino, _Lin._