56 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
grayish or slightly grayish yellow, often tinged with brown at base; 
those on anterior margin of posterior spiracle light brown, outwardly 
tinged with yellow; spiracular cover pale yellowish. 
Wings. — Bend of fourth vein normally a right angle, rarely a little 
more or less; anterior cross-vein behind end of first longitudinal; 
third vein bristly; costal spine vestigial; section V of costa about 
equal to section III; alulae fringed with hair; calypters whitish, 
outwardly fringed with white hair. 
Legs. — Dark; posterior trochanter with 'brush'; femur spindle- 
shaped, typically with five rows of bristles on anterior face, those of 
second and third (intermediate) rows rather short, directed outward 
along femur, sometimes almost appressed, often vestigial, especially 
those of third row which is occasionally wanting ; a weak row of bristles 
may be present on lower, posterior face, especially proximally; tibia 
usually curved; tarsus equal in length to tibia. Middle coxa with a 
single row of bristles; comb of femur well developed; submesotibial 
bristle strong. Anterior coxa with two rows of bristles. 
Chaetotaxy. — Anterior dorsocentrals much longer than vestiture 
of prescutum and as long as or longer than anterior postsuturals ; 
inner presuturals short; four pairs posterior dorsocentrals, last 
tw^o pairs the longest; prescutellar acrostichals present; three sterno- 
pleurals. 
Abdomen. — Lamellae of fourth ventral plate normally show a& 
approximated ridges bearing two parallel 'brushes.' 
Chaetotaxy. — Second segment without marginal bristles; third with 
two at center and with short, slender bristles between these and 
laterals; fourth with a complete row of bristles ending ventrally at 
forward turn of margin. 
Genital Segments. — First, generally gray pollinose except 
'humps' and sides near posterior margin, often tinged with reflecting 
colors of abdomen ; vestiture short; outline in profile somewhat con- 
vex; second, dull orange to yellowish, rarely brownish. Forceps 
prongs slightly convergent at tips. 
Genitalia. — 'Brushes' of fourth ventral plate extend the full 
length of inner edges of lamellae; base of plate with a subcircular 
membranous area at its center. About in line with median process, 
posterior plate of penis has a roundish or ridge-like protuberance on 
each side ; distal extremity broadened and having form of paired lateral 
kno])s; median and lateral processes somewhat membranous and sup- 
