Male Genital Armature of the Dermaptera. Part II 523 



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Zacher certainly attaches an exaggerated importance to the 

 armature of the preputial sack ; the presence of various chitin- 

 plates, denticulate pads, etc., may coincide with genera in some 

 instances, but I am convinced that they have only specific value. 



After a study of a considerable amount of material, I have 

 come to the conclusion that the best characters are afforded by the 

 metaparameres, which are of three main types, .the long, medium, 

 and short. The presence of elytra, whether rudimentary or not, 

 seems to have little generic value. 



The best specific characters are the shape of the pronotum, 

 the form of the forceps, and, above all, of the ninth sternite of the 

 male, or penultimate ventral segment, and the armature of the 

 sides of the sixth to ninth abdominal segments in the male, and 

 the sculpture of the abdomen. 



The Psalidte are rather heavily built, usually sombre-coloured 

 earwigs, with a strong tendency to brachypterism and apterism ; 

 they are to be found under stones, logs, etc., and species are 

 numerous in hot climates. As a rule, the area of each species is 

 rather restricted, but two, Anisolabis maritima and A. anmdijies, 

 have become cosmopolitan. 



The feature which characterizes the group is the great develop- 

 ment of the manubrium of the male, which is seldom less than one 

 and a half times, often three times, as long as the ninth sternite ; 

 it is narrow at the base, and dilated at the apex.* 



The metaparameres have a kind of false membrane, very 

 delicate and often difficult to see, and obscured by the preputial 

 sacks when in erection ; the blade is divided into two parts by a 

 kind of midrib. 



I take the opportunity of correcting a serious slip in my fasci- 

 cule on the Dermaptera in Wytsman's " Genera Insectorum," 

 p. 25, where in the table of genera of this group the metasternum 

 is given as rounded in the Psalidm, and truncate in the remaining 

 gri »ups : of course, for " metasternum " mesostemum should be read. 

 This is true of all known genera of the Psalidm except S/xmdox. 



After a prolonged study of a considerable amount of material, 

 I feel inclined to give up the task in despair; I can find no 

 character which will allow the division of the Psalidw into what 

 appear to be natural groupings, nor to separate the New World 

 from the Old "World forms. I have drafted dozens of synoptical 

 tables, only to destroy them afterwards in disgust ; I have erected, 

 in MS., dozens of new genera, only to reject them a few days later ; 

 and now I do not feel that 1 am one step nearer to finality than 

 when I started. I am convinced that Zacher's arrangement cannot 

 hold good ; that many of his genera are founded on merely specilic 

 characters ; that some of them may stand, but that others must go. 



* Trans. Ent. Soc. London, 1915, p. 270, pi. xxxii. 



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