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



Acerentulus Berlese. 



In this genus, sensu restricto, the following distinguishing characters may be 

 given: Tergal apodemes never twice forked laterally; both tergal plates and 

 apodemes present on the meso-, and metathorax and first eight abdominal seg- 

 ments; tarsi of front legs without row of spines. This genus is richest by far in 

 number of species of all the genera of Protura. 



Acerentulus oculatus, n. sp. 



A medium-sized species which has the thorax and first abdominal segment 

 somewhat paler than the rest of the body. Head about twice as long as broad 

 and strongly arched in front; pseudoculi (or ocelli?) dorso-lateral, conspicuous 

 and provided each with a hemispherical cornea-like structure; rostrum absent; 

 in front of eyes four transverse striations are present. Exposed part of pro- 

 thorax about two-thirds as long as wide. Meso-, and metathorax similar, the 

 latter broader than the former. Segments one to six inclusive of the abdomen 

 quite similar in shape; seven narrower and slightly longer; eight much smaller 

 than seven and with both striated band and pair of pectines. Some of tergal 

 apodemes, two to seven inclusively, but slightly antero-posteriorly arched, 

 squarishly thickened at the middle and branched laterally; most of tergal plates 

 with two transverse lines, only one of which is conspicuous. Tarsi of first pair 

 of legs about one and a third times as long as tibiae, and each terminated by a 

 long, stout claw which is curved only beyond its middle. Length, with seg- 

 ments slightly telescoped, 0.89 mm.; width, 0.20 mm. 



Type Cat. No. 24,584 U. S. N. M. 



Described from type specimen, taken at Takoma Park, Mary- 

 land, from decaying leaves. This species is most nearly related 

 to A. confinis (Berlese) of the described species but differs from 

 confinis in having the head about twice as long as broad instead 

 of about one and one-half times as long as broad, as well as in 

 other characters. It is a common species at Takoma Park. 



Acerentulus tenuiceps, n. sp. 



A good sized, well chitinized, yellow species. Head very long, over twice as 

 long as broad, somewhat squarish behind and cone-like in front; pseudoculi not 

 conspicuous, slightly dorsal of lateral in position; rostrum in the form of a 

 chitinous tubercle. Exposed part of prothorax not one-halt as long as the 

 mesothorax. Meso-, and metathorax large. Abdomen large, broadest at the 

 fourth or fifth segments; some of tergal apodemes thickened near their middle 

 and branched near their extremities, none of them strongly antero-posteriorly 

 arched; seventh abdominal segment similar in shape to the eighth but much 

 larger; eighth segment with transversely striated band and pair of pectines. 

 Anterior legs much larger than the others; tarsal claw of anterior legs very long, 

 curved only beyond its middle and without accessory spur at or by its base. 

 Length with segments slightly telescoped, 0.85 mm.; width, 0.15 mm. 



Type. Cat. No. 24,585 U. S. N. M. 



Description based on the type, a female taken from decaying 

 leaves at Takoma Park, Maryland. This species is most nearly 



