The single species from Rott, _Thanatites vetula_, is closely allied to the modern Thanaos, whose species are numerous and feed upon a variety of plants, belonging to the families Cruciferæ, Leguminosæ, Umbelliferæ, Cupuliferæ, Betulaceæ and Salicaceæ. Most of the genera belonging to its tribe feed upon Leguminosæ, and these are the usual food plants of the species Thanaos also; whence it is probable that Thanatites had a similar taste. Now in the very beds of Rott, in which this butterfly was found, occur species of Betula, Salix and Populus, with numerous Querci and no less than eleven genera of Leguminosæ, mostly belonging to the Papilionaceæ; they are Templetonia (1 species), Robinia (2), Colutea (1), Phaseolites (2), Sphinctolobium (1), Dalbergia (1), Hæmatoxylon (2), Gleditschia (2), Cassia (3), Ceratonia (1), and Acacia (2). It is probably among these, and perhaps with greatest probability among the species of Hæmatoxylon and Gleditschia, that the food plant of Thanatites must be sought. Should leaves be found, in which a portion is bent over as if to form a nest, they should be submitted to the scrutiny of some one familiar with the larval habitations of _Thanaos Tages_; and should traces of silken fastenings be found in connection with them, or the marks of nibbling at the edges, the plant to which they belong may be considered with strong probability as the food of _Thanatites vetula_.
The only butterfly found at Radoboj belonging to an extinct genus is _Mylothrites Pluto_, and this is a member of the same general group as Coliates, and feeds probably upon Leguminosæ; for it is not so closely allied to Delias as Coliates is, but is more nearly related to Hebomoia, one of whose species, found in the East Indias, feeds upon Capparis.[AP] One species of Phaseolites, one of Sophora and four of Cassia, namely: _C. hyberborea_ Ung., _C. phaseolites_ Ung., _C. lignitum_ Ung., and _C. ambigua_ Ung., are recorded from Radoboj, and as Cassia is a favorite food plant among the larger species of Danai at the present day, we may fairly presume one of these Cassiæ to have afforded nourishment to _Mylothrites Pluto_. Moreover, no less than thirty-one species of Leguminosæ in general, or between a ninth and a tenth of the whole known flora, are given by von Ettingshausen as occurring in Radoboj; so that in any case our Mylothrites must have found abundance of palatable food.