202 PROC. ENT. SOC. WASH., VOL. 23, NO. 9, DEC., 1921 



species so far reported from the Nearctic are less than one 

 millimeter long and are very poorly chitinized. This apparent 

 difference between the two faunas is probably due to the fact 

 that the writer has employed specialized methods of collection 

 which has revealed better the microproturans than have those 

 methods that have been used in Europe. Finally it should be 

 stated that the study of our Nearctic Proturans shows that the 

 group as a whole, at least as far as the Holarctic is concerned, is 

 one of marked unity; a unity in fact not found in the case of the 

 two other major groups of Apterygota, the Thysanura and the 

 Collembola. 



EXPLANATION OF PLATES. 



Fig. 1, Eosentomon vermiforme, n. sp., dorsal view of head, x 333; fig. 2, 

 Eosentomon vermiforme, n. sp., ventral abdominal appendages on left side, x 

 about 267; fig. 3, Eosentomon pallidum, n. sp., ventral view of left appendage of 

 second abdominal segment, together with a part of same segment, x 333; fig. 4, 

 Eosentomon minimum, n. sp., left labial palpus from below (camera lucida 

 drawing with oil immersion lens); fig. 5, Protentomon transitans, n. sp., abdominal 

 appendages of right side, lateral view, x 333; fig. 6, Acerentomon americanum, 

 n. sp., dorsal view of seventh abdominal segment, x 333; fig. 7, Acerentomon 

 conuris, n. sp., seventh abdominal segment from above, x 333; fig. 8, Acerentomon 

 conurus, n. sp., left maxillary palpus from outside (camera lucida drawing with 

 oil immersion lens); fig. 9, Acerentulus oculatus, n. sp., dorsal view of anterior 

 part of head, x 333; fig. 10, Acerentulus tenuiceps, n. sp., dorsal view of head, 

 x 333; fig. 11, Acerentulus tenuiceps, n. sp., dorsal view of dorso-lateral part of 

 eighth abdominal segment (oil immersion lens); fig. 12, Acerentuloides bicolor, 

 n. sp., dorsal view of seventh abdominal segment, x 333; fig. 13, Microentomon 

 minutum, n. sp., dorsal view of seventh abdominal segment, x 333. 



OBSERVATIONS RELATIVE TO RECENT RECOVERIES OF 

 PLEUROTROPIS EPIGONUS WALKER. (HYM.) 



BY J. S. WADE AND P. R. MYERS, U. S. Bureau of Entomology. 



It is the purpose, in the compilation of the data here submitted, 

 to recapitulate very briefly the more essential facts regarding 

 the introduction into this country from England of Pleurotropis 

 epigonus Walker, a well-known Chalcidoid parasite of the 

 Hessian fly Phytophaga destructor Say. It also seemed desirable 

 to collect the records of distribution, and to assemble chrono- 

 logically all available citations to the literature on the insect. 

 Acknowledgment is gratefully made to Mr. A. B. Gahan of 

 the Bureau of Entomology for much information furnished. 



The original description of the species by Francis Walker 

 appeared in 1839 under the name of Entedon epigonus Walker. 

 This later was found by Dr. Riley (who compared specimens 

 with Walker's type in the British Museum), to be synonymous 



