REVISION OF THE NORTH AMERICAN WASPS OF THE 

 SUBFAMILY PLATYGASTERINAE. 



By Robert M. Fouts, 



Of Washington, District of Columbia. 



INTRODUCTION. 



In taking up the study of the Superfamily Serphoidea in 1915 

 the writer experienced from the first great difficulty in identifying 

 the various wasps belonging to the large and important Family Platy- 

 gasteridae. It was in fact impossible to name any species with cer- 

 tainty by the use of the literature available. Ashmead 's Monograph 

 of the North American Proctotrypidae, the only work pretending to 

 deal in an exhaustive manner with the group as a whole, is very un- 

 satisfactory, and the present effort is intended to be a thorough revision 

 of a portion of it, namely, the Tribe II, Platygasterini. 



As to my method in drawing up this work I may say that I have 

 described fully all of the species known from America north of Mexico. 

 The descriptions are made, as far as possible, in a relative manner. 

 This enables me to omit many useless characteristics such as the pu- 

 bescence on the thorax, the shape and vestiture of the legs, etc. 

 Descriptions made in an absolute sense seem less useful. The reader 

 is distracted from points more worthy of his attention and valuable 

 time is thereby lost. It is only when one has the types that one can 

 generalize in this way. Isolated descriptions, especially in the large 

 and difficult genus Platygaster, should be made with attention to 

 detail. It is patent that the author of such a description could not 

 know absolutely which were the important characteristics and which 

 the unimportant. It is the duty of the monographer to eliminate 

 the commonplace and useless from such descriptions. I may say 

 finally that, except for the various drawings made by Ashmead, tnis 

 work entirely supplants that part of his Monograph dealing with the 

 Tribe Platygasterini. 



A Bausch & Lomb binocular microscope (No. 5 ocular and 24 mm. 

 objective) has been used in the study and comparison of specimens. 

 A disk micrometer, graduated to tenths of a millimeter was used for 



No. 2484 — Proceedings U. S. National Museum, Vol. 63, Art. I5». 



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