434 PROCEEDINGS OF THE NATIONAL MUSEUM vol. iis 



material, some of his published descriptions are so brief and general 

 that they could apply to many species within the genus. 



In more recent years additional species have been added by A. A. 

 Girault (1916-1920), A. B. Gahan (1922-1934), and the author of 

 tliis revision (1939-), among others. 



Source of Study Material 



A study of several collections was made in preparation for this 

 revision. With the aid of a grant. No. G-1308, from the National 

 Science Foundation it was possible to spend a sabbatical year studying 

 collections of this genus in the United States. Collections studied 

 included those of the U.S. National Museum, Washington, D.C., 

 Department of Agriculture, Ottawa, Canada, and Cornell University, 

 Ithaca, N.Y. In addition, collections from the Universities of 

 Oregon, North Dakota, Wisconsin, and Illinois, as well as my own 

 collections, were available and contained some new species and im- 

 portant host and distribution data. 



All available types in the United States and Canada have been 

 examined. Type material of a number of species has been lost or 

 destroj'ed. This is true for the two species described by Say 

 {Eurytoma studiosa and E. orhiculata), three species described by 

 Walsh {E. gigantea, E. bicolor, and E. auriceps), and E. solenozopheriae 

 Ashmead. Neotypes are designated for these species, and E. studiosa 

 and E. auriceps are redescribed below. 



Nineteen new species are described and several species, the original 

 descriptions of which were brief and inadequate, are redescribed. 



The hey to the 82 species treated in this revision is based on an 

 unpublished one by the late A. B. Gahan, formerly of the U.S. 

 Department of Agriculture, Division of Insects. Mr. Gahan's key 

 was modified and enlarged considerably. The key suffices for most 

 of the more distinct species, but for many of the species good key 

 characteristics have been difficult to find. Experience reveals certain 

 characteristics that may seem obvious to the worker constructing 

 the key but which are difficult to interpret by those unfamiliar with 

 the group. No clahn is made for a completely accurate and workable 

 key, but a first attempt must be tried at some time. It is hoped that 

 the present key will eventually lead to the preparation of a more 

 adequate one as weaknesses are discovered. 



In the course of preparing tliis revision, I have received help from 

 a number of people. Dr. B. D. Burks of the U.S. Department of 

 Agriculture, Entomology Kesearch Branch, Washington, D.C., and 

 Dr. Oswald Peck, Canada Department of Agriculture, Research 

 Branch, Ottawa, Canada, made available collections containing 



