2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 79 



ing of members of the Decatomini, and Eurytomini also, from galls 

 and other sources, will continue to increase, and thus supply within a 

 few years what may prove to be representatives of most of the species 

 of these tribes in our fauna. Only then may we pretend to produce a 

 complete revision of the tribe Decatomini. 



In another sense, also, the present study is in part tentative. The 

 limits of certain species, for example Decatoma dubia Walsh, D. 

 globull^ new species, and D. nigriceps Walsh, can not be determined 

 with precision until their habits can be studied in considerable 

 detail. An effort to separate the species on the basis of male geni- 

 talia has not been made, because adequate material of this sex is 

 not at hand. It is probable that the necessary technique for the 

 study of minute parts of these small insects can be developed, but 

 many additional specimens, obtained by careful rearing that involves 

 determination by experts of both the plant and animal hosts, need 

 to be provided before a comprehensive study of the taxonomic value 

 of male genitalia can be profitably undertaken. In view of the 

 great variations in color and size and sometimes sculpture and 

 dimensions the question of species limits, which constitutes the 

 chief problem in a study of this nature, is therefore not fully an- 

 swered. It has been possible, however, to identify with practical 

 certainty all specimens that came to my attention. 



Many specimens were dissected in balsam and permanently 

 mounted on slides with the expectation that valuable characters 

 might thus be discovered. I have concluded, however, that all the 

 characters that really prove to have value for distinguishing species 

 can be seen on the entire specimens by the aid of the ordinary 

 higher powers of a good binocular microscope. 



ACKNOWIiEDGMENTS 



I have been aided in this study by various institutions and persons 

 who have supplied specimens, provided instruments, or given advice 

 and criticism. Their assistance is appreciated. I am particularly 

 pleased to acknowledge my obligation to the board of trustees and 

 the chairmen of the Bache Fund, Prof. Ross G. Harrison, of Yale 

 University, and Prof. H. S. Jennings, of Johns Hopkins University, 

 for grants that made possible the initiation of this study at tlie 

 United States National Museum in the summer of 1926 and the 

 subsequent preparation of material for study and the execution of 

 drawings found in this paper. Funds under the administration of 

 Dean A. H. Daniels, of the gi-aduate school of the University of 

 Illinois, were made available for mounting large numbers of the 

 Kinsey specimens, and I am grateful for this sympathetic support. 



