400 Dr. David Sharp on ilie structure of the 



In order to make my descriptions intelligible, I must 

 briefly sketch the general conditions prevailing in the 

 Pentatoiniehe, as to the structure of the terminal (or 

 genital) segment in the male sex. 



First, it forms a cavity or chamber widely open 

 externally, which I shall call the terminal chamber, and 

 in this open chamber are placed the following structures, 

 viz : — 1. The part of the male organs through which 

 pass the membranous structures connected with the 

 ejaculatory duct ; this I shall call the oedeagus. 2. The 

 termination of the alimentary canal ; this is free and 

 very mobile, and forms a sort of tail : I shall therefore 

 call it the rectal-cauda. 3. Some accessory pieces or 

 appendages, viz., a, lateral, one on each side ; b, inferior, 

 a single piece. The general arrangement of these parts 

 is that the rectal-cauda is in the middle above, and 

 completely overlaps and covers the oedeagus, which is 

 usually so completely concealed that I had examined 

 many specimens without suspecting its existence until I 

 discovered it by dissection ; the lateral appendages are 

 placed near the side-walls of the segment, one on each 

 side, and are in many species very mobile, though in 

 other cases very little power of movement appears to be 

 present : the inferior accessory piece is placed on the 

 middle of the inferior part of the segment directly below 

 the termination of the rectal-cauda. 



These parts exist in all the Pentatomidce I have 

 examined, and though so variable in form from species 

 to species that they are not similar in any two I have 

 seen, yet they are in all clearly homologous. There is 

 another part, of a very peculiar and important nature, 

 that is nearly always (perhaps I might say absolutely 

 always) present, viz., a tubular or cylindrical structure, 

 fastened to the inner face of the floor of the chamber, 

 and completely surrounding the oedeagus ; it is, in fact, 

 a fence or hedge, open only above ; I will speak of it as 

 the theca. 



In order to complete this brief outline of the nomen- 

 clature I have used, I should add that the transverse 

 deflexed wall separating the anterior part of the segment 

 from the open posterior part is called the diaphragm, and 

 that there frequently exists on each side of this diaphragm 

 and close to the rectal-cauda a projection of variable 

 form, which I have called the superior lateral process. 



