PROBABLE FOOD-PLANTS OF TERTIARY CATERPILLARS. 



73 



A species of Delias, however, to which genus Coliates has been specially compared, 

 is stated to feed, not upon a leguminous plant, but upon Dioscorea, one of the Yam 

 family; and the presence in Aix of a species of a closely allied group, Smilax rotun- 

 diloba Sap., is announced by Count de Saporta. It is not improbable, therefore, 

 that Smilax rotundiloba was the food-plant of the larva of Collates Proserpina} 

 The fifth Aix species is Thaites Ruminiana. It is most nearly allied to Thais 

 of the present day, though it bears certain relations, as we have seen, to neighbor- 

 ing genera. Thais feeds principally at least upon Aristolochia^ and so, too, do 

 Ornithoptera, Archon and some genera of swallow-tails; indeed, this seems to be 

 a favorite food-plant with insects of this character. Parnassius, however, feeds on 

 Sedum, Telephium, Sempervivum and Corydalis, especially on the first-named, one 

 of the Crassulaceae ; but nothing very closely allied to this is specified by Sa- 

 porta from Aix; neither, also is Aristolochia, but it has been found not only in, 

 Radoboj * in the Mayencian, but also, according to Heer, at Hohe Rhonen in Swit- 

 zerland, which belongs to the Aquitanian, and has at least one plant {Laurus pri- 

 migenia Ung.) in common with Aix. It seems, therefore, highly probable that 

 either Aristolochia nervosa Heer, A.. Aesculapi Heer, or a distinct species of the 

 genus will yet be discovered at Aix,* and may then be considered, as with little 

 question, the food-plant of Thaites Ruminiana. If it be deemed hazardous to ven- 

 ture such an opinion, attention is called to the two following passages ; the first is 

 from the introduction to Heer's paper on the fossil insects of Aix:* "Dass indessen 

 auch Weiden oder Pappeln [Populus] sich vorhanden, dilrften der Bythoscopus 

 muscarius und die Aphrophora spumifera [Homoptera] anzeigen, deren analoge 

 lebende Arten besonders auf den Blattern und Zweigen dieser Baume sich umher- 

 treiben." The second is a note in the errata to the translation of Heer's work on 

 the Climate and Vegetation of the Tertiaries" by Gaudin: "Le Poacites ciliatus 



I Since this was written, Count Saporta writes me : ''I>e genre 

 Smilax e»t iin deB genres tertiaires les plu» frequent'*. J'ai au8»i 

 signal^ dans le dipAt Toi^in de St. Zacharie (^tage Tongrien \nK- 

 rieure [and therefore but eliglitlymore recent]) nno feuille qui m'a 

 paru devoir sc ranger parmi les Dioscovt^es." 



« An old writer in Fuessly's Magazin. writing from Italy, says 

 that Thais feeds in tliat louutry upon Querrus. Five species of 

 Qnenus are known from Aix, hut the statement in Fuessly's Mag- 

 azin has never, to my knowledge, been conlinncd. 



»*• Nous n'avons pas encore rencontre d'Ari»'tolocbia dans les 

 gypsesd'Aix; mais I'existence du genre dans le tertiaire moyen 



ne saurait dtre mise en question, depuis que nous avons entre les 

 mninR une superbe emprcinte de Radoboj (Aristolochia venusta 

 Sap.), qui denote une forme voisine des Aristuloches k fcuilles 

 persiftantes et demlH^oriaces, comme V A. reticulata Nutt. de Vir- 

 ginie.*' Saporta, loc. cit., 34'2-3. 



*In a recent letter from Count Saporta he remarks : " Relative- 

 ment au Thaites Rumiviann. je n'ai pas encore decouvert a Aix de 

 vestiges du genre Aristolochia, mais ce genre devait y exister." 



» Vierteljahrsschrilt natui-f. Geeellsch. Zurich, i. 12. 1836. 



' ilecherches sur lu Cliniat ct la Vegetation du pays tertiaire, 

 4to, 1861. 



