74 FOSSIL, BUTTERFLIES. 



Sap. n'est pas unc glume de Graminee, mais plutot line bractee ciliee cle Peuplier. 

 . . . Elle doit Otre probablement rapprochue cl'iine cmpreinte . . . prove- 

 naiit des memes couches et qui se rapporte egalement an genre Populus. Les 

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

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

 sont encore inconnues, comme celles de TAlnus 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 pretcr en 

 paleontologie les diverses branches de Fhistoire naturelle." 



The single species from Rott, Thanatites vet'tda, 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, Umbelliferse, Cupuliferae, Be- 

 tulacero and Salicacea?,. 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 Leguminosa^ 

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

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

 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 

 Hrematoxylon 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 Tayes; 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 vetnla. 



The only butterfly found at Radoboj belonging to an extinct genus is Mijlo- 

 f/ir/'tes Pluto, and this is a member of the same general group as Collates, and 

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

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



