June, '03] ENTOMOLOGICAL NEWS. 183 



On Some American Gomphinae (Odonata.) 



By Philip P. Calvert, Ph. D. 



University' of Pennsylvania, Philadelphia. 

 (With Plate VIII.) 



The following paper has grown out of some preliminary 

 studies on the Gomphinae for the Biologia Centrali- Americana 

 edited by Mr. F. D. Godnian, F.R.S., of London. 



I. On DIAPHLEBIA. 



In 1858, de Selys* compared Epigomphus pahidosus, of his 

 legion Gomphus, with Diaphlebia angustipennis , of his legion 

 Gomphoides, as to their similarity in the " front tres-deprime, 

 .... la coloration du corps . . . . le forme du bout des 

 ailes," but adds, " les triangles libres et leur proportion em- 

 pechent de passer plus loin la comparison." The discover}^ of 

 a second species of Diaphlebia^ D. semilibera, in which all the 

 triangles are free except the discoidal triangle of the hind 

 wangs, again led him to a comparison with Epigomplms, and 

 to point out the possibility of confusing them " si, par excep- 

 tion tous les triangles [of Diaphlebia'] se trouvaient libres. "f 

 He considered that the greater length of the triangle of the 

 hind wings and, in the males, the shape of the superior append- 

 ages and anal angle of the hind wings of Diaphlebia suffice 

 to avoid such confusion. 



He does not mention, however, that the same interesting 

 possible "exception" in this genus would also constitute an 

 exception to the primary character of the legion Gomphoides. 

 The possibility is almost realized in 07ie of two males described 

 h^Xow 2i?> Diaphlebia nexans n. sp., in which all the triangles 

 are free except the discoidal of the right hind wing (See Plate 

 VIII, fig. 5). The significance of such conditions as exist in 

 D. semilibera and D. tiexans may perhaps be that they indi- 

 catea genealogical transition from the legion Gomphoides to 

 the legion Gomphus via Diaphlebia and Epigomphus. This 



^ Monographic des Gomphines, p. 87. 



t Bulletin, Acad. Belg. (2) xxxiii, p. 198, 1869. 



