1P20.] 3 



though, as thel*e are several species closely allied to it already known, 

 it may prove to be an ally rather than P. imjjressa itself, for the ligvu*e 

 of the male sexual mechanism is not satisfactory for that of P. impressa, 

 though the discrepancies may be partially if not wholly due to fore- 

 shortening. 



The character of Phalidura that has most impressed systematic 

 writers is a peculiar development of forceps at the posterior extremity of 

 the body so that they have been compai-ed with those that are so well 

 known in earwigs {^Forjiculidae), and I propose to make use of that 

 character in a systematic manner to define the genera which at present 

 ai'e confined to one, and as to the limits of which from Talaurinus 

 authorities are not agreed. 



The differences in the last ventral plate are unusual. In the 

 Curciilionidae the rule is that the true last ventral is membranous with 

 a chitinised patch, differing in size and in form, on each side of the 

 middle, so that the segment may be said to consist of two pieces, or to be 

 "divided." This plate is entirely concealed in the bodv, and forms the 

 floor of the genital orifice through which the median lobe is extended in 

 functional activity, only the fork of the spiculum and its adjunct or 

 augments intervening between the median lobe and the ventral plate. 

 This is the case with most of the Ainycferidae, cf. AcantJiolopliiis, 

 Cubicorhi/iiclius^ etc. 



In TidauriuHS and its allies the two chitinous pieces of the plate 

 exhibit a remarkable series of develojiments wliich attains its maximum 

 in PlutUdura. These developments ap))ear to ine to be probably adequate 

 for purposes of taxonomy : and by adding to them the distinctions that 

 are found in the last dorsal and certain peculiar developments that exist 

 in connection with the extensive membrane that connects the true last 

 ventral with the penultimate, 1 have been able to di'aw up tliis paper. 



With Talauriiiiis I cannot deal at present, but I expect it will 

 prove more difticult than the Phalidurines, and I anticipate that the line 

 separating the two will have to be a matter of compromise. 



It may be well to remark that the terminal body-segment in 

 Khynchophora is not so simple as it appears on superficial inspection, 

 for it is the seat of infoldings that souietimes go to a great extent and 

 are only detected by examining the interior aspect of the segment. 

 Also that the intersegmental membranes may be extensive and comj)lexly 

 folded. In some of the Orders of insects {c r/. Lepidoptei-a ) the modified 

 terminal segments are treated as parts of the genitalia. In Coleoptera 

 tliev have been but little stmlied. 



b2 



