A contribution to our knowledge of the Stylopidae. 947 
honey yellow, hypopygium yellow except the dorsal piece which is 
grayish. 
Female not seen. 
Described from 24 male specimens, all bred from individuals of 
Polistes annularis Linn., at Austin, Texas, during May 1901, 
Xenos pallidus may be distinguished from X. peckit and X. ni- 
grescens by its smaller size, more slender form and lighter coloration 
as well as by the characters given in the table. 
Fig. B, a. Fig. B, b. 
Fig. B, a. Wing of Xenos peckii KIRBY d. b. Wing of Xenos pallidus n. sp. d. 
Xenos nigrescens N. sp. 
Male. Length 4.5 mm. Black above, abdomen often gray at base, 
head above piceous, antennae dark cinereous. Mandibles black at base, 
lighter at the tips. Palpi cinereous, indistinctly two-jointed, the second 
joint one-half as long as, and connate with the first ventrally, where 
no suture is visible; above it appears indistinctly constricted off from 
the first. Prothorax black or piceous above, somewhat lighter on the 
sides; elytra cinereous. Dorsum of thorax fusco-piceous, lighter on the 
sides and at tip of post-scutellum. Abdomen usually black, sometimes 
gray at base and with two indistinct longitudinal dark bands. Wings 
delicate, pale hyaline, much as in X. pallidus, except that the sub- 
costal nervure is interrupted near the middle as in X. peckü; all the 
posterior veins nearly obsolete. Body below in great part piceous, ab- 
domen black or gray below. Legs cinereous, darker above on femora, 
tibiae, and tarsi. 
Female. Length 9—10 mm. Exposed surface of head black on 
posterior two-thirds, orange on anterior one-third, the line dividing the 
