PROCEEDINGS OF THE NATIONAL, MUSEUM. 



VOL. 63. 



smaller twigs of trees. The fine suspending thread is usually several 

 inches, not uncommonly 8 to 10 inches, in length. It may be that 

 this suspension of the cocoons provides a certain degree of protection 

 against secondary parasites; still, I have always reared hyperpara- 

 sites in abimdance from field-collected cocoons of species of Meteorus. 

 In the following key, as also in the descriptions and discussions of 

 the various species, frequent reference is made to wing characters. 

 I have employed throughout this paper the terminology adopted by 

 Rohwer and Gahan in their "Horismology of the Hymenopterous 

 Wing." ® The explanation of the wing figure included in the present 



D 



Fig. 2. — A— VENTER, first abdominal segment of M. tibl\us, showing ventral margins of the 



TERGITE. B— venter, FIRST ABDOMINAL SEGMENT OF M. COMMUNIS. C— DORSUM, FIRST ABDOMINAL 

 SEGMENT OF M. COMMUNIS, SHOWING THE PAIR OF FOSSAE ON PETIOLE. D — VENTER, FIRST ABDOMINAL 

 SEGMENT OF M. INDAGATOR. E— VENTER, FIRST ABDOMINAL SEGMENT OF M. DIMIDLATUS. F — VENTER, 

 FIRST ABDOMINAL SEGMENT OF M. VULGARIS. G— VENTER, FIRST ABDOMINAL SEGMENT OF M. HYPHAN- 

 TRLAE. H — DORSUM, FIRST ABDOMINAL SEGMENT OF M. HYPnANTRL\.E, SHOWING ABSENCE OF FOSSAE ON 

 PETIOLE. 



paper will prevent any possible misunderstanding regarding the mean- 

 ing of the terms used. Much care has been taken in the selection of 

 characters employed in the key; yet, so wide is the variation occur- 

 ring in nearly aU species that identification of specimens representing 

 the extremes of their respective species will possibly occasion some 

 difiiculty. The presence or absence of the dorsal fossae on the petiole 

 is easily determined and this character serves to divide the genus into 

 two rather well-marked groups. The five species which are taken 

 out at the beginning of the key Ijecause they possess a broadening 

 divided radiellan cell, are also provided with a pair of dorsal fossae 

 on the petiole, and are most closely allied to communis. The degree 



< Proc. Ent. Soc. Wash., vol. 18, 1916, pp. 20-76. 



