278 Mr. E. Meyrick on the classification 



genitalia ; so far, that is, as I have been able to examine. 

 It is therefore certainly probable — since the other 

 families all, as a rule, have the uncus developed — that 

 the BotydidcB are also a terminal development. But we 

 need not be surprised if we find in the other families of 

 the group genera where the uncus is also obsolete ; 

 because the obsolescence of a character normally present 

 may occur at any time. It is for this reason that single 

 characters are not usually reliable for family separation. 

 Similarly, in neuration, when a vein disappears (which 

 in the higher groups — that is, all except the Tineina — 

 never occurs except by coincidence with another vein) it 

 can never reappear in the descendants of the genus ; 

 the two coincident veins cannot be separated (although 

 veins which are only partially coincident — i.e., stalked — 

 may be). The MusothnidcE are therefore also a terminal 

 group. I do not, however, propose to explain my views 

 of the process of development of the Pyralidina until 

 I have finished the remaining families, when they can 

 be stated more completely; I have only indicated as 

 much as is necessary to explain the family limits 

 adopted. I think the principles expressed above may be 

 briefly defined by saying that for systematic purposes 

 negative characters are of more importance than posi- 

 tive. 



As mentioned above, I have examined and employed 

 the structure of the genitalia in the male as giving 

 characters of family value in this group. In the 

 absence of information from other sources I do not feel 

 very secure of my results ; and I have not attempted 

 here to investigate specific differences, assuming that 

 such exist. Adopting the terminology of Mr. P. H. Gosse 

 in his memoir on the Papilionidce, I recognise the uncus 

 existing in a very similar form ; the scaphium I have found 

 occasionally distinct, but usually it appears to be absent ; 

 the harpes do not appear to be represented at all. The 

 clasping organs appear to consist of a pair of strong horny 

 valves, which may be either retractile and usually with- 

 drawn within the abdomen, or apparently permanently 

 exserted, only concealed by the anal tuft ; and sometimes 

 also of a pair of elongate claspers, which appear to be 

 prolongations of the integument of the abdomen, and 

 are more feeble than the valves ; these claspers are not 

 usually well-developed and often entirely absent, but 

 when present the valves are apparently modified and 



