288 THE SPICULIFERA. 



diversity prevails amongst these insects ; their organs, 

 which are in most cases of considerable size, being 

 sometimes far too short to be of any use in flight, and 

 sometimes completely rudimentary. When the wings 

 are fully developed, an equal diversity is seen in the 

 degree in which their membrane is traversed by veins : 

 they usually, as in the species selected for an example, 

 present distinct veins, forming cells on the disc of the 

 wing of much the same arrangement as in the other 

 Hymenoptera, whilst in many, especially of the smaller 

 species, the number both of veins and cells is greatly 

 reduced, until in some they vanish altogether. The 

 abdomen, too, varies greatly in its form, being some- 

 times long, slender, compressed, and truncated at the 

 extremity ; sometimes long and slender, but more or 

 less flattened vertically and rounded at the tip, some- 

 times shorter and somewhat ovate, or tapering gra- 

 dually from a broad base to a pointed apex; but in all 

 cases it is attached to the thorax by a slender stalk, 

 which however is sometimes inserted between the 

 posterior coxse, and sometimes, singularly enough, 

 quite upon the dorsal portion of the metathorax, not 

 far behind the line of insertion of the hinder wings. 

 The ovipositor is frequently more or less exserted, 

 sometimes equalling or surpassing the whole body of 

 the insect in length ; and even when it is not exposed 

 in this fashion, its point, or rather that of the bivalved 

 sheath in which it is enclosed, is usually perceptible 

 at the apex of the abdomen. 



Notwithstanding this great diversity of organi- 

 zation, however, all the species of this tribe *agree 

 very closely in their habits ; their ovipositor is always 

 employed simply in introducing their offspring into a 

 proper situation for its development, and with the 



