GENERAL CHARACTERS. 7 



i.e. connected with the thorax hy a more or less slender [)etiole or 

 footstalk. The terms "subsessile" and " subpetiolate" are modifica- 

 tions of the sessile and petiolate forms and 

 are characters not only difficult to descr'lie 

 by word or figure, but unsatisfactory and 

 l)erj)lexing. In the Heterogyna the petiole 

 is either scale-like or nod(/se, otlen binodosc, 

 and in the Tubulifera the nundier of visible 

 abdominal segments is usually reduced to 

 three, the remainder being modified into a 

 slender retractile tube, which is generally 

 concealed. The place of insertion of the 

 abdomen is at the aj>ex of the metathorax, 

 except in the anomalous family Evaniidie, where it is inserted on the 

 disk or very near the bsise of that segment. In the Ichneumonidae 

 the situation of the spiracles on each side of the first segment is fre- 

 •juently used as a character for separating some of the subfamilies. 

 In the females of Hymenoptera the abdomen is furnished with an 

 instrument applied in the different groups as a saw, borer or sting, 

 })rotected by sheaths and called the ovipositor, which is often more 

 or less exserted, sometimes to a great length in certain genera of 

 Ichneuraonidse. 



Fig 7. 



Fig. 8. 



Professor Westwood, in his " Introduction," etc., vol. ii, following 

 oliiefly the views of Latreille, divides the Order into two Sections, 

 viz. : Terebhantia and Aci'leata, the former having the abdomen 

 of the females furnished with an instrument employed as a saw or 

 borer for depositing the eggs ; and the latter having the abdomen of 

 the females (and workers) armed with a sting connected with a poison 

 reservoir, the antennae of the males 18-jointed, and of the females 

 rj-jointed. 



The Tkuebraxtia is then divided into two subsections, the first, 

 termed the Phytiphaga, having the abdomen sessile, hiding the base 

 of the posterior legs, the larvae with a well developed mandibulated 

 mouth, feeding upon vegetable matter, and containing the families 

 Ttidhredinifhe and Uroceridoe. The second subsection, the Ento- 

 inophaga (Pupivora Latr.), having the abdomen attached to the 

 thorax by a portion only of its transverse diameter, the larvae with 

 slij.ditly developed mandibulated trophi, and for the most part feeding 



