128 
Psyche 
[June 
families the origin of Rs (in the fore wing) has migrated basally to 
such an extent that this vein (Rs) is no longer attached to R, seeming 
to arise as a separate branch of M. So far as this trait is concerned, 
then, Triplosoba is more primitive than Protereismatidae or any other 
known mayflies. This is not to imply, of course, that the Triplosobidae 
were the ancestral stock from which the other Ephemeroptera arose; 
but they were also certainly a derivative of such a stock, having their 
own specializations. 
References 
Brongniart, C. 
1893 [1894]. Recherches pour servir a l’histoire des insectes fossiles des 
temps primaires. Soc. Industr. Minerale, Bull., 7:124-615, pis. 17- 
53; also published as These Fac. Sci. Paris, 821, pp. 1-494, pis. 
1-37. (All page and plate citations in the present paper refer to 
the These, since this is the only form of Brongniart’s work usually 
available.) 
Demoulin, G. 
1956. Nouvelle recherches sur Triplosoba pulchella (Brongniart). Inst. 
Roy. Sci. Nat. Belgique, 32:1-8. 
Handlirsch, A. 
1906. Die Fossilen Insekten, Wien. 
Lameere, A. 
1917. Revision sommaire des insectes fossiles du Stephanien de Com- 
mentry. Mus. Nat. Hist. Natur., Bull., 23 :141-20 1. 
Martynov, A. V. 
1924. The interpretation of the wing venation and tracheation of the 
Odonata and Agnatha. Rev. Russe Ent., 18:145-174 [Eng. transl., 
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Tillyard, R. J. 
1932. Kansas Permian insects. Part 15. The Order Plectoptera. Amer. 
Journ. Sci., 23:97-134. 
