Natural Order--_Phalænæ_. Larva, with sixteen feet; it has a circle of wart-like protuberances on each segment, from each of which spring a few strong bristles; pupa, smooth, with a few bristles at the tail; changes in a cocoon, which is singularly left partly open at one end. We have but one species of this order in Britain, Saturnia carpini;[52] but among exotics there is a great variety, some remarkable for the immense expanse of their wings.[53] Probably Phalæna Atlas of Linnæus is the centre of the group, and, if so, the centre and type of the class Lepidoptera. [52] Saturnia carpini is the Pavonia minor of Linnæus, who, apparently, considered it a variety of a completely different species: the retention of a name thus originating in error is not justifiable. [53] Drury has some fine figures of this order, particularly Vol. I. pl. xviii. 2; Vol. II. pl. v. 1, pl. vi. 2, pl. xi. 1, 2, pl. xiii. 2; Vol. III. pl. xix. pl. xxiv. pl. xxv. pl. xxxiv. I have previously given, in a note, a list of the genera which are usually considered as Bombyces, and ought, therefore, if properly placed, to be included in the sub-class Phalæna; five of those genera yet remain, and at present must be excluded from the sub-class: Penthophera, Heterogena, and Limacodes, because I know nothing of their history; Nudaria and Psyche, because, in the larva, pupa, and imago states, they have the habit and appearance of another class (Neuroptera). The time of their dwelling with Lepidoptera is over and gone; they have already occupied too long a position to which they were not entitled. The difficulty of assigning a situation to Limacodes I hope to see removed, as the larva is occasionally to be met with. I must also remark, that although I have proposed a situation for Endromis, I feel very doubtful as to its being the correct one. These doubts and difficulties will probably gain me much censure; but I must endeavour to shelter myself in some degree, by observing, that I am the first who has ever deviated from the original Linnæan arrangement of Lepidoptera, the first who has ever thought of appealing to nature in support of theory, or rather has waited for nature to supply him with theory; and surely some allowance is to be made for a first attempt of any kind. I would also plead the poverty of our British Fauna in the sub-class, and my almost entire ignorance of exotic Phalænæ. Even supposing myself acquainted with all our indigenous species, they will barely furnish a systematist with a clew to the truth: you may pick up a single link of a chain, yet fail to discover the length of that chain, or the situation in that chain which the link originally possessed.