1880.] PROF. WESrWOOD ON THE GENUS PERQA. 361 



tion of the cross veinlet at its extremity, whicli is sometimes quite 

 straight, 111 others much curved ; in one species it is sharply an^u- 

 lated m the middle (P. ivalkeri) ; and in another species \p 

 schiodtei) the female has occasionally a small supplemental spur, 

 extending from the middle of this angulated cross veinlet. The 

 closed cells vary in their extent, sometimes scarcely extendino- 

 beyond the stigma and sometimes reaching nearly to the hind mar- 

 gin of the wings. 



The legs are generally rather short, especially in the males, in 

 which sex they are thickened. The tarsi vary considerably in 

 length, being generally shorter than the tibicc ; but in the females 

 of P. lewmi, as well as in other species, the tarsi are more elon- 

 gated, with the joints flattened and the cushion on the underside 

 more developed. 



Dr. Leach divided the genus into as many sections as the species 

 with which he was acquainted, employing the antenna and wing- 

 cells as characteristic of his groups, which were as follows : — 



A. Alis antieis anteareolam laarginalem non pi'omineuti- 



bus (antennis articulo tertio duobus sequentibus lon- 

 giore). 



a. Areolis submarginalibus duabus primis confluen- 



tibus, ultima ad basin superne subacuminata ; 

 areola marginali elongata, antice et postice acumi- 



. ."'^'i^ ••■■,■ ; ■•- : ii]}.\.P.j,oUta. 



b. Ai-eohs submargmalibus perfectis, ultima basi ar- 



cuato-emarginata ; areola marginali elongata, an- 



tice et postice acuminata Sp. 2. P. bicolor. 



c. Areohs submarginalibus perfectis, ultima basi recta • 



areola marginali ovata '. Sp. 3. P. latreillii. 



B. AI« anticie ante areolam raarginalem prominens (areola 



submarginali ultima basi superne acuminata). 

 a. Areola marginali ovata; antennis artieulo tertio 



duobus sequentibus longiore Sp. 4. P. dorsalh. 



0. Areola margmali elongata angusta utrinque (postice 



pra'sertim) acuminata ; antennis articulis tertia et 



quarto suba^qualibus, tertio longiore, artieulo 



qumto prrecedente breviore Sp 5 P kirhii 



c. Areola marginali fere lineari, antice obtusa postice 



acutiuscula, antennis articulis tertio, quarto et 



qumto fere a^qualibus Sp. 6. P. ferri,ginea. 



I have not thought it necessary to carry out this principle of sub- 

 division mto the numerous species now known of the genus which 

 vyould have required a formidable tabulation of the specific dis- 

 tinctions of the insect,s with their sectional characters. Neither 

 have I thought it necessary to adopt the subgenus Pseudoperga, 

 proposed by II. Guerin-Meneville (in the text of the ' Icono4anhie 

 du Regne Animal, Ins.,' p. 395) for P. lewisii on account of the first 

 and second submarginal cells being confluent by the almost obsolete 

 condition of the transverse veinlet separating them in the ordinarv 

 species. •' 



Details of the natural history of two of the species, P. dorsalts 

 and P. lewmi, have been recorded, condensed abstracts of which will 



