186 NATURAL ARRANGEMENT OF INSECTS. 



denly dilated at its apex, and compressed. 2dly. The 

 Tryphonidce, in which the abdomen is generally clavated, 

 and either subsessile or petiolated, with also a scarcely 

 exserted ovipositor. Two species,, the Tryphon vari- 

 tarsus and pinguis, carry their eggs attached beneath 

 the apex of the venter. 3dly. In the Cryptida, the ab- 

 domen is always petiolated, and the ovipositor exserted, 

 and usually as long as the body. It is in this family 

 that the genus Pezomachus occurs, all of which are ap- 

 terous. 4thly. The Pimplidce succeed ; and in these 

 the abdomen is subsessile and depressed, and usually 

 very elongate, and with an elongated ovipositor, parti- 

 cularly conspicuous in the typical genera Pimpla and 

 Rhyssa; and Glypta exhibits its abdomen marked above 

 on each segment with two convergent depressions. Eu- 

 ceros, in this family, exhibits, like Joppa in the Ichneu- 

 monides, a suddenly compressed enlargement of the 

 antenna?. In the 5th family, the OphionidcB, the ab- 

 domen is laterally compressed, and shaped like a scimitar, 

 especially in the typical genera. In Pristomerus, in 

 this family, the femora are armed beneath with long 

 spines, a structure found also in Odontomerus, in the 

 next family, the 6th, or Xorididce, which are chiefly 

 distinguished by their globose heads. This tribe is suc- 

 ceeded by the Ichneumones adsciti, or Bracones. These 

 are distinguishable from the former, by having but one 

 recurrent nervure, and by the second submarginal cell, 

 when extant, being frequently larger than the first. 

 These have been separated into two primary divisions, 

 according to the structure of the mandibles : into, 1st, 

 the Endodonttes, in which these organs close as usual ; 

 and, 2dly, the Exodontees, in which they are apparently 

 distorted, curving outwards when closed, and never meet- 

 ing. The first division have been subdivided into Po- 

 lymorphi, consisting, as their name implies, of insects of 

 a variety of forms, and which seem a convenient recep- 

 tacle for such as will not associate with the other sub- 

 divisions ; and here Streblocera is conspicuous for its 

 remarkably distorted antennae. The second division is 



