418 Transactions of the Society. 



metaparameres characteristic of Dicrana, and no other genus, occurs 

 only in Africa. 



Without any desire to underrate the great value of his work, 

 I certainly think that Zacher overrates the importance of the 

 armature of the preputial sac, and I feel quite unable to grant 

 generic value to the rows of teeth, often very difficult to observe, 

 and so perhaps sometimes overlooked, and chitin pads and plates 

 in the preputial sac. I also consider the virga to afford specific 

 rather than generic characters, for we find great diversity in the 

 length of this organ in species that are undoubtedly closely 

 related, and, in my opinion, congeneric. 



In dealing with old and dry specimens, the virga is often difficult 

 or impossible to distinguish ; it may be shrivelled away, or dis- 

 solved out by the action of the potash. I certainly think that no 

 definite negative opinion on the virga should be formed till several 

 specimens have been examined, as its visibility differs very much 

 in different mounts. 



I consider that the most important family characters are 

 afforded by the metaparameres ; here we find a grouping into 

 kindred forms that often corresponds well enough with the geo- 

 graphical distribution. But these are after all only secondary 

 sexual characters, analogous to the forceps ; and just as we find 

 considerable plasticity in the latter, so we must not be surprised if 

 we find it also in the former. I think we are in the presence of 

 dimorphism in the cases of Euborellia sisera Burr and E. greeni 

 (see Part II.), where two individuals, externally indistinguishable, 

 often have quite difficult metaparameres. 



I am not alone in my opinion that Zacher overrates the value 

 of the genital armature for generic characters. It is no breach of 

 confidence to quote the words of so eminent an entomologist as my 

 old friend Dr. H. A. Krauss : " Ich freue mich, dass Sie trotz 

 Verhoeff & Zacher bei der Benutzung der ausseren Kennzeichen 

 fur die Systematik geblieben sind & die Spitzfindigkeit der 

 mannlichen Copulationsorgane erst in's Hintertreffn gestellt haben. 

 Schliesslich hatte man nur noch mit Virga, Praeputialsack & 



Parameren gearbeitet & das Wichtigste, das Aussere der Tiere, 

 ware vernachlassigt worden. Und in den Sammlungen waren nur 

 noch Budimente der Tiere mit abgeschnittener Abdomenspitze 

 zuruckgeblieben " ; also the distinguished Dermapterist Dr. A. 

 Borelli, who wr'tes me : " Credo come Lei che non bisogna fare 

 troppi generi basandosi unicamente sulla forma dei parameri o 

 sulla presenza di denti, strie o altri ornamente, d'altronde gli 

 apparati genitali non sono che uno dei caratteri, bisogna tenere 

 anche conto degli altri." 



The true earwigs fall into two groups, those with a pair of 

 penes, the Protodermaptera, and those with one, the Eudermaptera. 

 In the former group, each preputial sac takes its origin from the 



