sexual apparatus of Acentropus. 161 



organ presents decided, though small, differences in cer- 

 tain individuals. In Staudinger's examples of A. niveus, 

 in those from near Burton-on-Trent, and from Ringwood, 

 the apex is curved upwards into a small hook, and in 

 these there is also an appearance of a larger tooth within 

 the apex in front of the series of minute teeth on the 

 median dilatation. 



Mr. Dunning concluded his memoir by remarking, that 

 he was inclined to the opinion, that there were not facts 

 sufficient to justify us in considering that more than one 

 species of Acentropus has been satisfactorily proved to 

 exist, for which he retained the name 'niveus.' The 

 results of my examination of the genital apparatus, do not 

 place me in a position to disagree with him. Certainly, 

 there is nothing to justify the wholesale multiplication of 

 species recently effected by Baron Von Nolcken. Yet I 

 feel inclined to reserve any opinion on the matter when 

 taken into consideration with the enormous discrepancy 

 in the alar development of the females, about which there 

 evidently exists some amount of mystery not yet un- 

 ravelled. In the males, also, there is a very considerable 

 difference in the form of the wings in individuals from 

 different localities, though it may be that this difference 

 may be better attributed to local than to specific influ- 

 ences. And, furthermore, I do not consider that suffi- 

 cient attention has yet been paid to the characters 

 presented by the genital apparatus in Lepidoptera to 

 warrant us in assuming that in them, specific characters 

 may always be as marked as they are in Trichoptera, &c. 



The students of Neuroptera, using the term in its 

 broad sense, have sometimes been twitted with the remark 

 that they pay too much attention to these characters. 

 This has never been said by a Neuropterist of a Neurop- 

 terist. In their Order each case is considered according 

 to its merits. Large groups of species, e. g. the restricted 

 family LibelluUna, present scarcely any important differ- 

 ences in these characters in generic structure, and but 

 slight specific difference; others show a constant spe- 

 cific difference in some portion of the apparatus; and 

 there are, finally, many genera in which each species has 

 an arrangement of parts totally different from that of its 

 nearest allies. Thus wide specific difierence may exist 

 in other characters, combined with an inappreciable 

 amount of it in these alone ; but I have never yet found 



