18S3.] 



161 



THE DISTINCTIVE AND SEXUAL CHARACTERS OF CEEYSOFA 

 FLAVA, SCOPOLI, AND CH. VITTATA, WESMAEL. 



BY ROBERT McLACHLxVN, F.R.S., &c. 



I have more than once been asked by friends, interested in Euro- 

 pean Neuroptera, whether I did not consider it possible that the two 

 species of Chrysopa above-named (both tolerably common in Bintain) 

 might not be only sexes of one species distinguished by the form of 

 the costal margin of the anterior-wings. My reply has always been 

 to the effect that I believed them to be distinct, and that I had the 

 sexes of both. This I felt sure of ; but it is only this moment that I 

 have become aware of a remarkable difference in wing-details in the 

 sexes of Gh.Jlava, and in calling attention to this I will allude to the 

 specific characters : — 



Ch. pxava. 

 Costal margin of anterior wings ex- 

 cised in botli sexes. In the $ the margin 

 is much elevated at the base, and then 

 almost suddenly depressed, so that the 

 costal area is wide at the base and then 

 becomes almost suddenly very narrow. 

 In the $ the excision is shallow and very 

 gradual (sometimes almost impercepti- 

 ble), so that tlie costal area narroios 

 gradually, and not suddenly. 



In the (J the costal nervules arc much 

 incrassated from the point where the 

 costal area becomes suddenly narrowed. 

 In the ? these nervules are slender the 

 whole length of the area. 



Superior anal appendages of <J long 

 and stout, subcylindrical, the obtuse tips 

 curved upward and inward ; they are 

 as long as, or longer than, the inferior 

 appendage, which latter is in the form 

 of a very broad triangular plate, concave 

 within, the apex somewhat suddenly 

 acuminate, turned upward between the 

 tips of the superior appendages, and 

 ending in a tuft of stiff hairs. 



Ch. vittata. 

 Costal margin of anterior wings nearly 

 straight (or slightly convex) in both sexes, 

 the costal area narrowing gradually. 



In both sexes the costal nervules are 

 all slender. 



Superior anal appendages of <J much 

 shorter {only about half the length of 

 the inferior appendage) , stout, irregularly 

 sub-cylindrical, dilated externally in the 

 basal portion, with a constriction before 

 the apex, the tips turned inward but 

 scarcely upward. Inferior appendage 

 similar to that of flava, but naiTower, 

 the acuminate apical portion longer. 



I am not able to give anal characters for the ? , but distinctive 

 points probably exist in the fresh insects. 



The nomenclature is that adopted by Hagen, and I think it would 

 be unwise to alter it, but it seems to me impossible to exactly define 



o 



