904 AN INTRODUCTION TO ENTOMOLOGY 



In the form of the ovipositor and in its position when at rest the 



R^+s^M, 



Fig. 1 1 43. — V^fings oi Oryssus abietinus. (From MacGillivray.) 



Ory'ssidas differ from all other H^Tnenoptera. The following account 

 of this organ is that of Rohwer and Cushman ('17). 



Lying below and on each side of the eighth tergite in the female is a large 

 heavily chitinized plate, the two together forming ventrally a channel for the re- 

 ception of the ovi- 

 positor, and each 

 bearing at its tip a 

 small triangular ap- 

 pendage. These 

 plates apparently 

 represent the fused 

 ninth and tenth ter- 

 gites which are lon- 

 gitudinally divided 

 dorsally (Fig. 1144, 

 9T and loT), and 

 the appendages are 

 apparently the cer- 

 ci (Fig. 1 144, c); the 

 eighth sternite is in- 

 ternal and lies 

 above and some- 

 what behind the 

 ninth, and is rep- 

 resented by two 

 triangular plates, 

 from the upper 

 angle of which or- 

 iginate the lancets 

 (first gonopophy- 

 ses) (Fig. 1 145, //); 



Fig. 1 144. — Lateral aspect of abdomen of 

 the female of Oryssus. (After Rohwer 

 and Cushman.) 



Fig. 1 145. — Details of the ovipositor of Oryssus: 9 T, 10 T, 

 ninth and tenth tergites; 8 S, eighth sternite; 9 S, ninth 

 sternite; //, lancet;/, lance; sh, sheath; 0, ovipositor; c, 

 cerci. (After Rohwer and Cushman.) 



the ninth sternite is also internal, lying below and in front of the eighth 

 and represented by two more or less triangular plates which extend postero- 

 ventral; the lance (second gonopophyses) originates from the inner ends of these 

 plates and becomes fused a short distance cephalad of its origin (Fig. 1145, /); 



