I have no doubt this is the _Pap. Statira_ of Cramer; it is found only in Brazil, and has been erroneously considered by Godart and Latreille as a variety of _C. Jugurthina_, an Indian insect, and which in fact is not in itself a species, being no other than the female of _C. Alcmeone_, as an attentive examination of a vast number of both, collected in Java by Dr. Horsfield, enabled me to ascertain. The extraordinary prolongation of the last joint of the palpi, and the white borderless spots beneath, which are never silvered, will distinguish this species through all the variations; in the ground colour of its wings, which in no two specimens are exactly alike, and one before me is nearly white; the lesser snowy dot is sometimes very obscure, and often wanting; but the prolongation of the palpi is even expressed in Cramer's figure above quoted. I have examined about a dozen specimens, mostly captured by myself, and all have been females; and I strongly suspect future and more decided observations will prove _C. Evadne_ to be the other sex: it has the palpi lengthened, though in a less degree; and the articulations of the antennae in both insects will be found somewhat thickened at their termination when viewed under a magnifier, a peculiarity I have seen in no other species; and although I have examined near thirty specimens of _C. Evadne_, they have invariably proved to be males. The palpi in this insect will be found at variance with the generic character now given; a striking proof that in a natural system no single part can be taken as an unerring criterion for generic distinction, without making it eventually an artificial one. The _Colias Drya_ of Fabricius has the same formation of palpi, but is a totally different insect. * * * * * Pl. 6 [Illustration] COLIAS Leachiana. _Leachian Colias._ * * * * * GENERIC CHARACTER.--See Pl. 5. * * * * * SPECIFIC CHARACTER. _C. alis subrotundatis, integris, virescenti-albidis, anticis supra fulvis, margine punctoque medio nigris, singulis subtus macula centrali ferruginea._ Encycl. Method. (Male) wings slightly rounded, entire, greenish white; anterior pair above orange, at their tips, margin, and central dot black: each pair beneath with a central ferrugineous spot. Female ----? C. Leachiana. _Godart in Encycl. Method._ vol. ix. p. 91. * * * * * In size this insect is the largest of the genus yet discovered; it was first noticed by Godart, who has given it the name of my learned and valued friend, Dr. W. E. Leach, of the British Museum, whose talents are too well known to need any eulogium in this place.