OF WASHINGTON, VOLUME XIV, 1912. 133 



Head smooth, about 1.25 times as long as wide, broadest at basal third, 

 cheeks evenly arcuate to eyes and base of head; vertex flattened, angulate in 

 front, the sides forming an angle of 125, and with a pair of prominent, post- 

 antennal bristles equal in length to segments 1 -(-2 of antennae; frontal costa 

 notched at 90; two pairs of bristles behind eyes, the inner pair shorter 

 and subequal to, or rather longer than, a third pair between eyes. Eyes 

 rudimentary, only about three facets visible in lateral profile. Ocelli and 

 ocellar pigment entirely wanting. Antennae long and slender, about 2.7 

 times as long as head; base of segment 1 hidden by vertex; form and struc- 

 ture well shown in figure (PI. v, fig. 1). 



Prothorax trapezoidal, about 1.2 times as long as head and (inclusive of 

 coxe) about 1.4 times as broad as long and 1.8 times as broad at base as 

 at apex, with faint anastomosing lines of sculpture; notum not attaining 

 lateral margins, separated from the pleural plate and the coxa by a longi- 

 tudinal, sinuate suture extending from the anterior angle to thebM.<e;im- 

 diad to this suture often a longitudinal carina attaining about middle of 

 prothorax; several short bristles present in addition to the long pair at the 

 posterior angles (PI. V, fig. 2). Pterothorax reduced, subequal in width to 

 prothorax; mesonotum with a pair of prominent bristles on each side near 

 anterior angles; mesosternum with two prominent bristles at extreme lat- 

 eral margin, metasternum with one. Legs exceedingly stout, fore and hind 

 femora greatly enlarged, the former nearly as wide as head, and the latter 

 two-thirds as wide as long. Wings lacking. 



Abdomen about 2.66 times as long as wide, broadest at about segment 

 6, weak and very blunt at apex; terminal bristles long, slender, and trans- 

 parent, a lateral pair on segment 9 about five-sixths as long as greatest 

 width of abdomen. 



Measurements of holotype: Length 0.823 mm.; head, length 0.089mm., 

 width 0.071 mm.; prothorax, length 0.105 mm., width 0.147 mm.; ptero- 

 thorax, width 0.144 mm.; abdomen, width 0.176 mm. Antennal segments: 

 1, 23 M; 2, 27 M; 3, 38 M ; 4, 35 M ; 5, 26 M ; 6, 28 M ; 7, 26 M ; 8, 36 M ; total 

 length of antenna, 0.24 mm.; width at segment 4, 0.016 mm. 



Male. Length about 0.75 mm. Last two abdominal segments distinctly 

 yellowish. General structure as in female. Fore femur toothed on inner 

 margin near base; inner side of fore tibia produced at apex in a stout, acute 

 tooth. Dorsum of head apparently minutely granulate, certain of these 

 granules darker and arranged in anastomosing lines. Apex of abdomen 

 suggestive of that of Chirothrips, all bristles slender. Accessory sexual 

 organs heavily chitinized; testes not visible. 



Described from 3 females and 1 male, as follows: Homer, 

 Illinois, October 3, 1908, under loose bark on shellbark hick- 

 ory tree, J. D. H., 1 female; Olney, Illinois, November 19, 

 1908, from branch of post oak (Qncrcus stcllata Wang.), L. 

 M. Smith, 1 female; Illinois, July, 1909, in burrows of freshly- 

 hatched larva? of Oncidcrcs ting nlata Say in dead hickory twig, 



