292 PROCEEDTXaS OF THE NATIONAL MUSEUM. vol. xxxi. 



besides Doctor Kohl in Vienna, I am deepl.y indebted to Dr. R. Rathbun, 

 assistant secretary of the Smithsonian Institution; and to Dr. L. O. 

 Howard, of the U. S. Department of Agriculture; Dr. W. H. Ashmead, 

 of the National Museum; to Dr. Henry Skinner, of the American Ento- 

 mological Society, for the loan of material from the collection at Phila- 

 delphia; to Mr. Samuel Henshaw, of Harvard College; Mr. William 

 Beutenmiiller, of the American Museum of Natural History; Dr. W. ,1. 

 Holland, of the Carnegie Museum; Prof. J. H. Comstock, of Cornell 

 University; and Sir Daniel Morris, of Barbados, for the loan of mate- 

 rial in their charge, besides nearly thirty other persons who have in 

 a similar wa}^ aided me in bringing together for study the largest accu- 

 mulation of insects of this group ever made in this country. 



At the time the work was begun it was proposed to limit its scope 

 to the United States. It soon became evident, however, that it would 

 be necessary to include Mexico and the West Indies, and the discovery 

 of species in Arizona not heretofore reported north of Venezuela has 

 led to the study of Central and South Amercan forms also. The inten- 

 tion in this paper now is to include all the Chlorioninw known to occur 

 in North America to the Isthmus of Panama and the West Indies, 

 though the South American forms may perhaps be treated subse- 

 quently. It is the hope of the writer to be able to extend his studies 

 to the Sceliphroninte and to the Sphecinie (Ammophilinfe of authors) 

 though such study as he has given to this last group has shown that its 

 present condition is anything but encouraging for systematic work. 



CLASSIFICATION AND NOMENCLATURE. 



For some 3"ears the classification of the wasps has been the su))ject 

 of many differences of opinion, the term Sphegoidea, as used by Ash- 

 mead, having been considered by some writers as including a number 

 of families, while others have regarded it as containing but one. 



The main differences of these views may be found in Doctor Ash- 

 mead's paper, '^ so that it is unnecessary to consider them here. The 

 studies of the writer, however, have led him to an opinion somewhat 

 different from any of those there given so far as the value of the minor 

 groups is concerned. 



The different species included in this paper, for the most part, fall 

 without difficulty into one or another of six groups recognized by 

 Ashmead as genera. In some cases, however, species are met with 

 which are intermediate in character, linking different groups together 

 in such a way that it becomes difficult to characterize them without 

 making many exceptions, though in any two of these there are forms 

 which differ widely from each other. This is very suggestive of the 

 idea that the individuals of an old genus are now beginning to diverge 

 in different directions, and that the result will ultimately be the for- 



oCanadian Entomologist, XXXI, p. 145 et seq. 



