1888.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 485 



factorily in this genus, and therefore use neither the term nor any sub- 

 stitute. What I take to be the true penis or intromittent organ, Baly 

 calls the " duct," It is entirely membranous and therefor.- useless in 

 classification. The variations mentioned by Baly are largely individ- 

 ual, and will vary according as the specimen has or has not copulated. 



Iu the females I have found no guide at all to a nomenclature. The 

 structures, as they appear in Laehnostertia, consist of a pair of broad in- 

 ferior plates, of a generally similar shape and which I do not specif- 

 ically refer to in this paper, as the other structures render their use un- 

 necessary. They may however in other groups prove of value. Above 

 these are a pair of superior plates, generally smaller and narrower than 

 the inferior, and much more variable. When the organs are most fully 

 developed these plates are excised at their point of superior union, 

 and are surmounted by a pubic process very variable in shape in the 

 species, and this organ is the one which furnishes most of the charac- 

 ters used in this paper. Where this structure is not present the supe- 

 rior plates are much more specialized, and the variations are then spe- 

 cific. In a very few species the corneous characters are reduced to a 

 single pair of imperfectly chitiuized plates, and there are then no visible 

 differences to be observed. I have found that the more uusymmetrical 

 and the more developed the character of the male, the stronger will be 

 found the characters of the female. As th * male characters become 

 symmetrical the female characters become less prominent, the pubic 

 process first disappearing, until with the least development of the males 

 the corneous characters disappear almost entirely and at all events are 

 useless for specific identification. 



I shall not undertake very full verbal descriptions of these parts, but 

 prefer to let my figures answer most of the questions. A reference to 

 these figures will show my reason very clearly, as no words could ac- 

 curately describe the peculiar turnings and twistings. The mobility of 

 the male claspers is not great in any case, and in some species they are 

 absolutely immobile, being united in front and forming a c Knplete ring. 

 The modification in these species is not very great, and in the females 

 the characters are, of course, correspondingly weak. It is not easy to 

 watch coition iu these insects, though specimens in coitu are not un- 

 common in some species. Tristis is most usually found in coitu. hirti- 

 cula next, iu my experience, and the others comparatively rare. Tristis 

 is one of those in which the claspers are not mobile, and no observa 

 tions could be made of their use. Hirticula has claspers which are de- 

 cidedly dissimilar, while the female structures are well marked. I 

 uever succeeded in seeing the union of the sexes, though quite a num- 

 ber were taken united. From these specimens I tried to see the method 

 of union, but was not very successful, as the male claspers so com 

 pletely envelope the female parts that little could be seen of them. I 

 did see, however, that the claspers held more particularly the pubic 

 process, and that the inferior plates are not at all concerned in the 



