10 
confusing assemblage of different species under the same name, and, 
worse than this, the bringing together of representatives of different 
genera under a. single species. This is well illustrated in the species 
cornigcr and subalbatus, under which names specimens were found 
grouped in the collections of the American Entomological Society 
which belong to at least four distinct genera. In cases like this it is 
sometimes difficult, particularly where the type specimens are lost, to 
decide to which genus the species bearing the original name should be 
assigned. The difficulties of the case have been greatly enhanced by 
the fact that Norton, who has described most of our species, allowed 
many of his types to be destroyed through his indifference in later life, 
after he had ceased studying the group, thus vitiating much of the excel- 
lent work of his earlier years. A box of his type specimens examined 
by me, which had recently been returned to the Entomological Society 
of Philadelphia, was so thoroughly disintegrated by vermin that scarcely 
a recognizable fragment remained. 
The very careful work done in the last few years by Fr. W. Konow, 
of Fuerstenberg, Germany, particularly in separating the old bulky 
genus Nematus into some nine genera, has made it possible to take up 
this group much more satisfactorily than heretofore, and in the prepa- 
ration of this paper Konow's system has been the basis of the classifi- 
cation adopted. 
Sources of material, — The proper placing in the new genera of the 
Species formerly included in Nematus, which in scarcely an instance 
can be gathered from the original descriptions, has necessitated the 
examination of all the old types of Norton, Cresson, and others, and 
these have been redescribed, whenever obtainable. The material in 
the genus Nematus in the collection of the Ainericaif Entomological 
Society, which includes all of Cresson's and Norton's types, so far as 
they have been preserved, has been very kindly placed at my disposal. 
I have also had the National collection at hand, and material from a 
number of private collections, the most important of which are the 
Nematines from Cornell University, kindly loaned by Professor Corn- 
stock, and the types of Messrs. Harrington, Dyar, Forbes, Ashmead, 
and McGillivray. The types of Provancher's two species were also 
very kindly obtained for me by Abbe Iluard. The types of Kirby's 
species and of a few others described abroad I have been unable to 
examine and refer generically, and the original descriptions of these, 
together with the descriptions of the lost types of Norton, are included 
in an appendix. 
Structure and terminology. — In recharacterizing the old species and 
working up the large amount of new material which has accumulated, 
parts hitherto rarely used have been referred to and terms repeat- 
edly employed throughout the descriptions which would be unfamiliar 
to most students. The following description of the salient characters 
used in the descriptions and the terminology will therefore be valuable. 
