The Entomologist of the present day must naturally remain under some uncertainty as to the identity of the Fabrician Papilio Pylades, since no figure whatever has hitherto appeared in elucidation of this rare Papilio; and in this instance, as in almost every other, whatever advantage we may be able to derive from the very accurate and elaborate descriptions of our author, it would be absurd to deny that a faithful delineation of the insect described, is not essentially requisite, in order to determine with perfect satisfaction, the precise species Fabricius had intended. But, besides the want of a correct delineation, there is yet another circumstance, not, perhaps, at present known, which might have tended also to perpetuate this ambiguity, had it not been in our power to explain it: the intimation of which, it is presumed, will be considered useful by the scientific Entomologist. Previous to the time of Fabricius this elegant species had been unnoticed by any author. Fabricius describes it in his Entomologia Systematica, and refers for the specimen so described to the Cabinet of Mr. Francillon. That the insect, to which he adverts, was included in that celebrated cabinet, we are well assured from our own inspection, but it stood there unaccompanied by any indication of its being a specimen described by Fabricius, or even a Fabrician species. The truth is, that Professor Fabricius, upon this occasion, as in some others, took his description, not from the specimen itself, but from the drawings of Mr. Jones, of Chelsea, which had been copied from the specimen in the cabinet of Mr. Francillon, and it was to the drawing therefore of Mr. Jones, and not to the specimen of Mr. Francillon’s cabinet that Fabricius annexed the name of Pylades. Those drawings must for this reason be now considered as the only positive memorial of the identity of the Fabrician species, Papilio Pylades, that remains extant at this time. The figures, it may be added, which are submitted in the annexed plate, are faithful copies from the original drawings of Mr. Jones, so inscribed in the hand writing of Fabricius, a circumstance that must remove every shade of doubt as to the individual object to which Fabricius had assigned that appellation.