516 HEMIPTERA. 



foul odorous fluid. Lacaze-Duthiers has given a sectional view 

 of Ranatni (Fig. 516 ; v, dorsal vessel ; i, intestine ; n, ner- 

 vous cord) which shows the relation of the elements of an 

 abdominal segment, t, is the tcrgum ; em, the epimerum : 

 ES, the episternum, and s, the sternum. 



The ovipositor and the genital armature are generall}- con- 

 cealed within the tip of the abdomen, being rareh' exserted so 

 as to form a prominent part of the body. It differs grcatl}' in 

 its development, and is difficult to reduce to a common tvpe. 

 Lacaze-Duthiers states that we may consider the abdomen of 

 the Hemiptera as consisting of ten or eleven segments, accoid- 

 ing as we consider the horny ring, lying between the abdomen 

 and thorax as the basal ring of the abdomen, oi- not. He re- 

 gards the former Anew as the true one. This author contends 

 that in Plod the tergum of the first and second abdominal 

 segments (proto and deutotergites) are coal- 



>^ V ^< esced, and tliat the original sutures are marked 



by simple striii;, Avhile at the opposite end of 

 s ' the abdomen the genital and anal outlets are 

 Fig- sitj- separated by three rings, i.e.^ the eighth, 



ninth and tenth. 



In the a cadi dee and Phytocoris the ovipositor is per- 

 fect and nuich as described in the Ilymenoptera. In the 

 •Fnlgoridai, Nancoris, Ploa and Notonecta, the eighth 

 segment is complete, while the ovipositor is more or less in- 

 complete, and it often happens tliat a reunion of secondary 

 pieces represents a principal piece, and that the elements of 

 the two i)<)stgenital rings are articulated togetlier by overla})- 

 ping each other. 



In Ranatra as Avell as Nepa is a third modification of the 

 ovipositor, where the postgenital segment is incomplete, and 

 the sternal appendages and sternum of the segment bearing 

 the ovipositor only remain, the other parts being aborted. In 

 the Pentatomids and Cimex there is no ovipositor, but the 

 Mborted elements are more or less developed, so as to be 

 identifiable. 



The nervous SA'stem consists, besides those of the head, of 

 tvio thoracic ganglia, of which the anterior is the smaller, which 

 send off two main trunks to the abdomen. 



