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



reflection, to conclude that the Nearctic Proturan fauna must 

 be much richer in species than would be supposed if we should 

 base a conclusion upon what has been known in the past of the 

 species occurring in Europe or reported from the world. 



In presenting the descriptions of these new species the writer 

 wishes to acknowledge his indebtedness to Mr. H. S. Barber of 

 this society for the many helpful suggestions he has made in 

 regard to the method of studying living specimens and the 

 preparation of mounted material. 



Descriptions of Genera and Species. 



The ten new species described in this paper fall into three 

 genera recognized by Berlese or into the new genera here 

 created, of which there are three. 



Eosentomon Berlese. 



Species of the genus Eosentomon differ from all the other Proturans in possess- 

 ing tracheae and in having all pairs of the abdominal appendages large and 

 two-segmented. 



Eosentomon vermiforme, n. sp. 



A medium sized but very long species. Head long, being fully twice as long 

 as wide; pseudoculi entirely lateral in position and in the form of irregular pits; 

 mouth-parts conspicuous; rostrum present, reaching the tips of extended maxil- 

 lary palpi. Exposed portion of prothorax about twice, as broad as long. Meso-, 

 and metathorax of about the same length but in the latter slightly the longer; 

 spiracles conspicuous, ventro-lateral. Abdomen very long, broadest at the 

 fourth segment and all tergal plates distinctly yellowish; tergal apodemes 

 slightly thickened toward the center, not antero-posteriorly arched and un- 

 branched laterally; seventh abdominal segment equal to the eighth in length, 

 the latter slightly narrower than the former and considerably narrower at its 

 posterior margin than at its anterior margin. Abdominal appendages very 

 slender, those of the first pair being about one-third as broad as long. Legs 

 moderate; first pair extending beyond the rostrum by the full length of the 

 tarsi and about one-half the length of the tibiae, and each leg ending in a tarsal 

 claw which is of about the same length as those on the other legs but is less 

 strongly curved. Total length, slightly extended, 1.32 mm.; width, 0.16 mm. 



Type Cat. No. 24,578 U. S. N. M. 



Described from a single specimen, a female, collected at 

 Takoma Park, Maryland, from decaying leaves. This species 

 differs from all the described species in being more slender and 

 worm-like. It is rare at Takoma Park. 



Eosentomon pallidum, n. sp. 



A small, white species. Head broad, about two-thirds as broad as long; 

 pseudoculi lateral, inconspicuous; rostrum minute; maxillary palpi when exten- 

 ded long, conspicuous, in this state equaling in length one-half the width of the 



