74 FOSSIL BUTTERFLIES. 



Sap. n'est pas une glume de Graminec, mais plutot une bractee cilice cle Peuplier. 

 . . . Elle doit etre probablemcnt rapprochee d'une empreinte . . . prove- 

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

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

 1'existence, a 1'epoque des gypses d'Aix, d'une espece de Peuplier dont les feuilles 

 sont encore inconnues, comme celles de 1'Alnus cryptophylla Sap., mais que 

 M. Heer avait indique d'avance, en se fondant sur 1'observation d'un insecte fossile, 

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

 paleontologie les diverses branches de 1'histoire naturelle." 



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

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

 belonging to the families Cruciferse, Leguminosse, Umbelliferge, Cupuliferaa, Be- 

 tulaceas and Salicaceae. Most of the genera belonging to its tribe feed upon 

 Leguminosa?, and these are the usual food plants of the species Thanaos also; 

 whence it is probable that Thanatites had a similar taste. JSTow 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 Lcguminosae, 

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

 (2), Colutea (1), Phaseolites (2), Sphinctolobium (1), Dalbergia (1), Ha3matoxy- 

 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 

 Hsematoxylon 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 Thanaos 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- 

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

 feeds probably upon Leguminosse; for it is not so closely allied to Delias as Coll- 

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



