_T. alis subdiaphanis, sulphureis, subtus immaculatis. Anticis supra apice nigris, posticis (in maribus) margine antico basi gibbosis. Foem. ----?_ Wings sub-diaphanous, pale sulphur; beneath immaculate. Anterior, above with a black marginal tip; posterior (in the male) with the fore-margin gibbous at the base. Female ----? Pieris Elvina. _Godart in Encycl. Method, p._ 158. _no._ 67. * * * * * This is one of the smallest of Butterflies, and from the extreme delicacy of its form seems to sanction with truth the poetic idea of living "but for a day." It is found in Brazil, inhabiting only the deepest forests, as if fearful its little life would be endangered by the scorching rays of a tropical sun: in these sombre shades it is seen to fly slowly and feebly near those spots where a ray of the sun has partially entered the thick canopy of foliage above, which is frequently fifty or sixty feet from the ground. The genus I have now placed it in belongs to the _Coliadae_, and appears to connect that family with the _Pieridae_: their distinctions are obviously marked and very constant in all the species I have yet seen, and which are tropical: of these, seven I discovered in Brazil; three or four more are natives of the southern extremity of North America; and Dr. Horsfield has four or five from Java. I know of none from Africa. Their size in general is very small. I think this species is the _Pieris Elvina_ of Godart; although the insect he mentions as the female is in reality that of his _Pieris Neda_. The true female I have never seen; I suspect it will want the gibbous curve on the hinder wings of the male, which sex is, indeed, not common, and is generally much smaller, and sometimes half the size only, of the figure. _Papilio Nicippe_ of Cramer (tab. 210. fig. C. D.) strictly belongs to this genus, though placed in that of _Colias_ by Godart, as well as his _Pieris Agave_, _Hecabe_, and doubtless many others not now before me. * * * * * Pl. 23 [Illustration] MITRA vittata. _Ribbon Mitre._ * * * * * CHARACTER GENERICUS. _Testa inaequaliter fusiformis, spira producta attenuata; labio exteriore intus edentato. Columella plicata_. DIVISIONES. I. _Apertura angusta, linearis, supra angulata, infra subcontracta._ _Mitrae vulpecula, plicata, &c._ OBS. _Testa plerumque longitudinaliter plicata, aequaliter fusiformis, labio exteriore laevi leviter undulato, interiore ad apicem intra crassato; gula striata._ II. _Apertura supra acuminata, infra angusta, extrinsecus curvata._ _Voluta mitra-abbatis._ Chemnitz, &c. OBS. _Testa plerumque spira elongata, apertura ad basin angustata, siphone superiore parvo aut nullo._ III. _Apertura supra acuminata, extrinsecus recta, infra rotundata, dilatata, vel effusa._