64 t'ROCEEDINOS OF THE NATIONAL MUSEUM. vol.49. 



close to the mandibles or arcuated anteriorly leaving a transverse, 

 elliptical opening between; antennae filiform. Thorax rather short 

 and robust, the parapsidal grooves present or absent; anterior 

 wings with three cubital cells, radial cell complete (open in the 

 genus Ademon) and terminating at or somewhat before the wing 

 apex though never shorter on the anterior margin of the wing than 

 the length of the stigma, submedian cell usually a little longer than 

 the median cell, anal cell never divided by a transverse nervure; 

 posterior wing with the radius usually effaced, the submedian cell as 

 measured on the median nervure at least one-third the length of the 

 median. Legs normal, the posterior tibial spurs short. Abdomen 

 inserted between the posterior coxae, subsessile or subpetiolate, 

 usually shorter than the combined head and thorax, ovate or ellip- 

 tical, the apical segments often somewhat retracted in the female; 

 ovipositor variable, more often concealed or very short but frequently 

 as long as the abdomen or even longer. 



Many Opimae are not readily separated from some of the smaller 

 Braconinae while others can easily be mistaken for small Alysiids. 

 They can be distinguished from Braconines, however, by the longer 

 submedian ceU of the hind wing and the slightly different character 

 of the opening between the clypeus and mandibles. From Alysiids 

 they may always be distinguished by the mandibles. 



The group offers a few good characters for the separation of species 

 but does not yield itself readily to separation into well-defined genera. 

 Many of the recorded genera are based upon trivial and unreliable 

 characters which make their retention impossible. 



American writers have confined themselves almost entirely to 

 descriptions of isolated species in this group. Dr. W. H. Ashmead 

 has given a generic synopsis in his Classification of the Ichneumon- 

 Flies which is, however, largely a translation from Foerster. Cres- 

 son, Provancher, Ashmead, Viereck, and the Avriter have published 

 descriptions of species. Of those described by Provancher, only four 

 species are properly placed in Opiinae. Several of Ashmead's species 

 also prove to belong in other groups of the Braconidae while four spe- 

 cies described by him as Alysiids are really Opiines. 



A number of forms are known to the writer, descriptions of which 

 are not included in this paper for the reason that they are repre- 

 sented only by imperfect specimens or specimens accompanied by 

 insufficient data. 



Species of Opiinae have been recorded as parasitic on Dipterous, 

 Coleopterous, and Lepidoperous insects. The usual hosts are phy- 

 tophagous Diptera, belonging to the families Agromyzidae, Trype- 

 tidae, Anthomyidae, and related families, but there can be little doubt 

 that some species do attack Lepidopterous leaf-miners. That any are 

 parasitic on Coleoptera remains to be proven. 



