AMERICAN APTERA. 413 



Cephalothorax about two-thirds as broad as long ; lamellae promi- 

 nent, about two-thirds as long as cephalothorax, narrow at the poste- 

 rior part, the anterior part being about one-fourth as broad as the 

 lamellae are long ; lamellae with prominent cusps ; translarnellae incom- 

 plete, being interrupted medially. Lateral lamellae present, three- 

 fifths as long as cephalothorax, very narrow. A rather prominent 

 tectopedium for leg one is present. Lamellar hairs simple, straight, 

 directed forwards and somewhat longer than the lamellae from which 

 they extend. Interlamellar hairs situated approximate to posterior 

 margin of cephalothorax, similar to lamellar hairs. The anterior 

 lateral hairs spring from the lateral lamellae. They are stout, pecti- 

 nate, almost straight and about as long as the lamellae. Pseudostigma 

 funnel-shaped, extending one-third its length above the surface of 

 cephalothorax ; pseudostigmatic organ two-thirds as long as lamellae, 

 clavate, dentate, directed forwards and away from median plane. 



Abdomen about three-fifths as broad as long, ptermorphae attached 

 to the anterior two-thirds of the abdomen, truncate in front and not 

 extending quite to the anterior margin of abdomen ; anterior free edge 

 of pteromorphae straight. Genital covers almost rectangular, slightly 

 broader anteriorly than posteriorly, situated about one and one-half 

 times their length in front of the larger anal covers. Anal covers half 

 as long again as genital covers, triangular and situated almost approxi- 

 mate to the posterior margin of ventral plate. Abdomen hairless. 



Anterior pair of legs a little longer than the cephalothorax ; tarsus 

 and tibia subequal. Tactile hair of tibia one, situated at the dorsal, 

 distal aspect of segment, about three times as long as the segment itself. 

 The femur of leg two bears on its lateral surface a small, narrow blade 

 with a large cusp at its distal end. This blade is represented in the 

 femur of leg one by a small chitinous ridge with a small process at its 

 distal end. The legs each bear several stout, curved, pectinate bristles. 

 Unguis tridactyle. 



Length, 0.42 mm. ; breadth, 0.26 mm. 



Under bark and in moss. Collected by the writer at Urbana, 

 Illinois. Many specimens. 



Oribata clavata n. sp, 



(Plate XV., Fig. 20.) 



Light brown ; integument of medium thickness, surface smooth. 



No demarcation between cephalothorax and abdomen. No median 

 lamellae, but a pair of narrow, lateral lamellae which arise at the pseudo- 

 stigmata and extend about two-thirds the distance to the tip of the 

 cephalothorax. Lateral lamellae broadest at the posterior end and 

 gradually narrowing anteriorly until they disappear. No translamella. 

 No lameliar hairs or anterior lateral hairs. Interlamellar hairs situated 

 almost in front of pseudostigmata, about as long as the pseudostigmatic 



TRANS. AM. ENT. SOC, XXXV. NOVEMBER, 1909. 



