STUDIES ON PERILLUS BIOCULATUS FAB. 79 
opaque, nearly crescent shaped in outline but the anterior margin recti- 
linear, inner half with a shallow sulcus which deepens and leads into 
the ostiole; ostiole situated slightly laterad of a line drawn through 
lateral extremities of adjacent coxae. In circumcinctus the ostiolar 
peritreme is narrower, its length equal to a little more than three times 
the width. Hemelytra rather closely and finely punctate; membrane 
extending slightly beyond tip of abdomen, dark fuscous to black. 
Venter rather deeply but finely punctate, the punctures becoming 
obsolete near median line. Ventral spine reaching to middle of pos- 
terior coxae. Spiracles surrounded by black which forms a spot equal 
to at least three times the diameter of spiracle. Males with a quadrate 
area of dense, closely appressed, silvery pubescence each side of median 
line on segments five to seven but limited to anterior margin on seventh 
segment. Male genital claspers nearly triangular but the dorsal margin 
distinctly sulcate in outline. In circumcinctus the dorsal margin of 
genital clasper is practically rectilinear, the apex being rather broadly 
rounded while in bioculatus the apex is acute. 
Legs typical for the genus; the anterior femora with a prominent 
tubercle or blunt spine situated on ventral surface, distant from the 
apex a space equal to diameter of femur. Rarely a specimen may be 
noted in which the tubercle is scarcely apparent. 
Color Varieties 
White color form. In this form the background is white with 
markings of black and brown. Head brown, becoming black at base. 
Antennae black, segments I, II, and base of III, brown to reddish. 
Pronotum with basal one-third brown, frequently black, basal angles 
not obscured ; callosities covered by black, each with a nearly quadrate 
spot, separated by white on median line of disk; occasionally speci- 
mens occur in which the black spots join, thus forming a transverse 
black bar. Pleura black, usually showing ivory white irregularly on 
disk of each sclerite. Scutellam with black longitudinally along middle, 
becoming wider toward base and usually notched with white at middle 
of base; the roughly punctate and depressed basal half of lateral mar- 
gins also black. Clavius except basal angle, and outer half of corium 
except apex, black; thus with embolium, inner half and apex of corium 
white; inner half of corium frequently with white area much reduced ; 
membrane always dark fuscous or black. Legs dark brown, tibia 
becoming white on middle one-third, tarsi blackish. Venter black each 
side of ventral spine but not extending laterally to the spiracle on 
