50 Bulletin of the Brooklyn Entomological Society Vol. XV 



A few of the species differ only very slightly in the genital 

 claspers, and just enough to cause one to wonder if there could 

 be such variation of size and structure within a species. In 

 order to get additional evidence on this point the writer has made 

 a careful study of the aedeagus and its chitinous parts and was 

 rewarded by finding some very definite and interesting struc- 

 tures, characters which correlate perfectly with the small differ- 

 ences found in the claspers. In the genus Phytocoris the tip of 

 the penis, or perhaps better called the median lobe of the sedeagus, 

 contains a chitinous process, representing the terminal chitinous 

 sclerite of that organ. After a careful comparison with the 

 work of Sharp and Muir^ on the structure of the sedeagus in 

 Coleoptera, the writer feels sure that this terminal chitinous 

 process can be homblogized with that structure which they have 

 designated as the flagellum, an armature of the internal sac of 

 the median lobe. The species most closely related to eximius 

 have a flagellum bearing strong chitinous teeth, which in various 

 modifications give distinct specific characters, while in the species 

 examined which have an irrorate or conspurcate membrane and 

 are related to inops and fumatus, the flagellum is devoid of teeth 

 yet has a distinctive shape in each species. The writer has ex- 

 amined from four to six males in most of the species and in no 

 instance has found any variation in the structures that would 

 lead to confusion between the most closely related species. 



Specimens to be used for this purpose may be placed in a 

 moist chamber and when sufficiently relaxed the genital segment 

 may easily be removed by using two needles sharpened like 

 chisels. The structures may then be picked out in a watch glass 

 containing 30 per cent, alcohol, later to be mounted on a triangle 

 placed on the pin beneath the insect. If we are tO' understand 

 the variations or differences which v>^e see in closely related forms 

 we cannot afford to neglect a consideration of the structure of 

 the aedeagus when working out the species. Once the species are 

 worked out on this basis, no doubt superficial characters will be 

 discovered which may be used for ordinary determination of the 

 species. 



2 Trans. Ent. Soc. London, 1912, pp. 477-642. 



