74 FOSSIL BUTTERFLIES. 



Sap. n'est pas une glume de Graminec, mais pliitot line bractee ciliee de Peuplier. 

 . . . Elle doit etre probablement rapproch^e d'une empreinte . . . prove- 

 nant des memes couches et qui se rapporte egalement au genre Populus. Les 

 organes voisins de ceux du Pop. Eiiphratica Oliv. dans la nature actuelle denotent 

 Texistence, a I'epoque des gypses d'Aix, d'une espece de Peuplier dent les feuilles 

 sont encore inconnues, comrae celles de I'Alnus cryptophylla Sap., mais que 

 M. Heer avait indique d'avance, en se fondant sur I'observation d'un insecte fossile, 

 le Bythoscopus muscarius! Nouvelle preuve du secours que peuvent se preter en 

 paleontologie les diverses branches de I'histoire naturelle." 



The single species from Rott, Thanatites vetula, is closely allied to the mod- 

 em Thanaos, whose species are numerous and feed upon a variety of plants, 

 belonging to the families Cruciferse, Leguminosae, Umbelliferse, Cupuliferae, Be- 

 tnlace.TO and Salicacese. Most of the genera belonging to its tribe feed upon 

 Leguminosae, 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 Leguminosae, 

 mostly belonging to the Papilionaceae ; they are Templetonia (1 species), Robinia 

 (2), Colutea (1), Phaseolites (2), Sphinctolobium (1), Dalbergia (1), Haematoxy- 

 lon (2), Gleditschia (2), Cassia (3), Ceratonia (1), and Acacia (2). It is proba- 

 bly among these, and perhaps with greatest probability among the species of 

 Haematoxylon 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 habita- 

 tions of TJianaos Tages; and should traces of silken fastenings be found in con- 

 nection 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 Mylo- 

 thritea Pluto, and this is a member of the same general group as Collates, and 

 feeds probably upon Leguminosae; for it is not so closely allied to Delias as Coli- 

 ates is, but is more nearly related to Hebomoia, one of whose species, found in the 



