Natural Order--_Cossi_. The larva is depressed; naked, except a very few scattered hairs; has sixteen feet; lives through one or more winters; never rolls itself in a ring when touched; feeds on the solid interior woody parts of vegetables. The pupa generally changes in a tough oval cocoon, interwoven with particles of its food. It has a double ring of raised denticulations of each segment of the abdomen, by means of which it is endowed with a considerable power of locomotion. The genus Zeuzera is very near the point of contact with the Bombyces. In Zeuzera there is much resemblance to the antennæ of Gastropacha. One genus, or group of genera, I expect will prove to be Stygia, a native of New-Holland. A second, at the point of contact with Sesia in Sphinx, must be Ægeria; thus retaining its place among British insects, immediately between Sesia and Cossus.[46] This is the first of a series of the most beautiful instances of approach, or rather, of what ought to be termed _relations of analogy_, that any system has ever previously disclosed. As a few words will again be necessary on this subject, I refrain from any further observation here, than merely requesting the reader to examine how minutely the Sphinx characters are appropriated by a true lignivorous Phalæna, which cannot be said, in any of its prior and principal states, to have the most distant approach to Sphinx. A third genus is, probably, the strange and paradoxical exotic Oiketicos, which has been minutely described in the _Linnæan Transactions_; and a fourth is Hepialus.[47] This genus has some slight points in which it differs from the others of the order already known, the larva being radicivorous only, seldom or never ascending internally the stems of plants: it changes in the earth. [46] It is a most singular chance that these genera should have been placed so naturally, as the cause of this proximity has never before been even hinted at. [47] Another type of Hepialus is figured in Drury, Vol. II. pl. xiii. 2.