No. 2315. TRIBES OP ICHNEUMONINAE—CUSHMAN AND ROHWER. 387 



posing the following arrangement of tribes we have therefore taken 

 into consideration what we know of larval structure, nature of the 

 host, and relation of parasite to host. We have found that the 

 structure of the ovipositor and of the terminal segments in the 

 female have been developed similarly in genera which have similar 

 larval structures and host relations. These characters in the female 

 are of such nature that they can be easily seen and expressed briejfly 

 and positively. We have therefore considered it advisable to 

 present a key based entirely on the female, making use of sexual and 

 secondary sexual characters. We recommend the use of this key to 

 beginners and others unfamiliar with the group and believe that less 

 difficulty will be experienced in its use than in the use of the key 

 in which the secondary sexual characters are eliminated. This 

 last mentioned key, while not entirely satisfactory, serves to dis- 

 tinguish the tribes which we believe to be represented among the 

 genera studied and sets forth the best 

 characters applicable to both sexes. 



There are three new terms which are 

 used in this paper, and the authors ex- 

 pect to make use of these terms in 

 future works. They may be defined as 

 follows : 



A perpendicular rbcrveUus (fig. 1,/, g) 

 is one in which the anterior end is op- 

 posite the posterior end, that is, one in fig. i.-nervelli: o,6andc,reclivous; 

 which a line drawn touching both the ^ and «,inclivous;/and g,¥EnPE^- 



, . . , DICXJLAE. 



anterior and posterior ends is at right 



angles to the longitudinal axis of the submediallan cell. Other 



authors have called this a continuous or interstitial nervellus. 



An inclivous nervdlus (fig. 1, d, e) is one in which the anterior end 

 is nearer the base of the wing than is the posterior end. This has 

 heretofore been spoken of as an antefurcal nervellus. 



A reclivous nervellus (fig. 1, a,h, c) is one in which the posterior 

 end is nearer the base of the wing than is the anterior end. This 

 has heretofore been spoken of as a postfurcal nervellus. 



We have substituted the terms inclivous and reclivous for the 

 ambiguous and unsatisfactory terms antefurcal and postfurcal; and 

 have adopted the less used term perpendicular because we believe 

 that it is less confusing and more in keeping with the terms incliv- 

 ous and reclivous. The terms interstitial, antefurcal, and post- 

 furcal are used in the usual sense for such veins as the nervulus and 

 recurrents and in this sense are easily understood and in keeping 

 with the exact meaning of the words. 



