somewhat as if due to attrition; especially in the cell on either side of the discoidal spot, at the extreme base of the lower median interspace, and along the lower border of the medio-submedian interspace. Length of wing, 15·75mm., length of inner border, 9·5mm.; breadth of wing across the middle, 7·25mm., breadth of wing across outer margin, 9·5mm.. Tertiaries of Aix, Provence, France. Museum of the City of Marseilles. COMPARATIVE AGE OF FOSSIL BUTTERFLIES. All the well determined fossil butterflies come from one of three localities, Aix, Rott and Radoboj, all belonging to the tertiaries of Europe. Others are reported, as will be seen further on, to have been found in Prussian amber; and it is not in the least improbable that they have been or may be. These would be of about the same age as the oldest of the others, those of Aix. Of the Aix fossils, which belong to the upper Eocene, or to speak more definitely, the Ligurian, _Neorinopis sepulta_, _Lethites Reynesii_, _Thaites Ruminiana_ and _Pamphilites abdita_ (the first described by Boisduval, the rest by myself) come from the calcareous marls of the gypsum quarries, the only bed in which insects had been found when visited by Messrs. Murchison and Lyell in 1829. _Coliates Proserpina_, however, described here for the first time, was taken from strata beneath these, and therefore, at least until we have more precise knowledge concerning the remains of butterfly larvæ in amber, may be considered the oldest known butterfly. Count de Saporta writes me concerning this fossil, the discovery of which is due to him, as follows:—“Cette empreinte ne provient pas des platrières même, c’est à dire des galeries qui servent à l’exploitation du Gypse; mais d’une assise ou groupe de couches immédiatement inférieure. Vous verrez cette provenance indiquée pour un grand nombre de mes espèces; dans ce cas, elles ne proviennent par des ouvriers mais je les ai recueillies moi même en suivant les lits sur les points où ils affleurent au dehors.” The next in order, approaching recent times, are the lignite beds of Rott in the basin of the Rhine, which belong to the Aquitanian or the upper part of the lower Miocene. _Thanatites vetula_ (described by Hayden) is the only butterfly known from this division of the Tertiaries. The most recent beds containing fossil butterflies are the lacustrine deposits of Radoboj in Croatia, Austria. These belong to the Mayencian or lower portion of the middle Miocene, and have furnished _Eugonia atava_, _Mylothrites Pluto_, another fragment possibly referable to Mylothrites, and _Pontia Freyeri_, all described by Heer. Two of the genera of these more recent beds contain representatives now living in the same region; but none of the older beds have yet furnished butterflies referable to modern genera.