240 ENTOMOLOGICAL NEWS [xxxii, '21 



An examination of the specimens of this species shows it 

 to be quite different from Eosentomon ivJieclcri Silvestri. 

 Silvestri's species belongs to the family Eosentomidae, which 

 family is characterized by the presence of a tracheal system and 

 by having all the vestigial appendages of the abdomen two-seg- 

 mented. The species here described belongs to the family 

 Acerentomidae, which family is characterized by having no 

 tracheal system and by having the second and third pairs of 

 vestigial appendages of the abdomen much more reduced than 

 the first pair and only one-segmented. The formal description 

 of the species follows: 



Acerentulus barberi, new species. 



$. Color in life a uniform yellow, which gives strong reflections 

 when in the direct sunlight. Head long, broadest slightly in front of 

 the posterior margin ; labrum not produced into a process ; pseudoculi 

 inconspicuous. 



Prothorax very short, about twice as broad as long, and slightly 

 broader than the head, provided above with a transverse row of four 

 setae, the outer being slightly the shortest. Mesothorax broader than 

 long and about twice as long as prothorax, sides convex, its longest 

 lateral seta equal to about one-half its width ; metathorax longer and 

 broader than prothorax and broader than long, sides slightly convex and 

 .somewhat divergent, longest lateral seta equal to one-half the width 

 of thoracic segment itself. 



Abdomen of medium/ length, segments increasing in width from I to 

 111, then decreasing gradually to VIII; VII twice as broad as long and 

 with sides almost parallel, but seen to converge slightly toward the 

 rear; VIII similar to VII in shape, but much smaller, with a band near 

 its anterior margin marked with microscopic longitudinal striations ; 

 segments IX, X and XI very short and ring-like; XII longer and 

 broadly rounded on its free margin. During life the last four seg- 

 ments of the abdomen are held much of the time almost completely 

 telescoped into VIII. Tergal apodemes present on first eight abdominal 

 segments, when viewed from above, seen to be only very slightly curved 

 and laterally branched. Dorsal setae of abdomen moderate, the longest 

 ones on segments II and III being scarcely equal to one-half the widths 

 of these segments. Vestigial appendages of first abdominal segment 

 conspicuous, about as broad as tibia III, first segment fully twice as 

 long as broad and cylindrical, last segment a truncated cone, about as 

 long as broad at the base ; vestigial appendages II and III subequal, being 

 minute and cone-shaped. 



Legs moderate ; first pair almost twice as long as the subequal last 

 two pairs. Claw of leg I very long. bein<? about half as long as the tar- 

 sus, straight for most of its length, but hooked toward the end. 



Length with abdomen about normal, LOS mm.; width at the region 

 of the third abdominal segment, 0.22 mm. 



Type localitv. Takoma Park, Maryland. Type. Cat. No, 

 24,162, U. S. N. M. 



