46 IOWA STUDIES IN NATURAL HISTORY 
anteriorly, the vertex raised and smooth. Antennae slender, blackish, the 
second segment paler, the first segment stout, shortest, the apical segment 
longest. Rostrum slender, blackish, reaching to midcoxae. Pronotum with 
anterior lobe smooth, impunctured, the remainder of its surface except 
posterior margin and thickened, white lateral edges deeply, coarsely and 
somewhat irregularly punctured; transverse impressed line broad but not 
reaching the lateral margins which obliquely approach the head thus ren- 
dering the pronotum distinctly narrower anteriorly than at base. Scutellum 
shining, coarsely, remotely punctured on middle, the punctures along the 
margin more or less confluent; extreme tip somewhat impressed and broad- 
ly rounded. Corium coarsely, rather regularly punctured, the punctures a 
little larger and denser at the base, shallower and finer on the posterior 
part of the disk; costal margin narrowly edged with white; a smooth cres- 
cent-shaped white mark is often present near the postero-lateral angle; 
posterior margin subtruncate, a little sinuate near the inner angle; mem- 
brane brown, the base thickened towards the inner angle; apical margin 
thinner, paler; five veins more or less plainly visible, two of which are 
sometimes forked at the tip. Venter deep black, shining, moderately con- 
vex, the sides very densely and moderately finely punctate, the disk very 
finely and sparsely punctate; edge of connexivum smooth, white at least 
on three apical segments, sometimes on all the segments. All the sternal 
plates shining but the odoriferous apparatus is dull black; the ostiole is 
very small and opens into a narrow groove which gradually becomes evanes- 
cent laterally; the groove is situated on a raised, crescentic and spatula- 
like plate which reaches three-fourths the distance from the ostiole to the 
margin; the plate is convex on the posterior border and rounded at the 
extremity. Legs black, the tibiae with a smooth white streak on outer side 
and with weak and rather sparsely placed spines arranged in rows; tarsi 
piceous, thickly set with yellowish hairs; coxae subtransversely striate. 
Length, 4.0-7.0 mm. Width across pronotum, 2.5-3.5 mm. 
This species is subject to some variation, both sexual and indi- 
vidual. The emargination on the front of the head varies among 
individuals of the same sex but is usually less distinct in the 
males. Often the males lack the white spots on the corium but 
these spots are also sometimes lacking in the females. Indeed, 
the extent and shape of this white spot, even when present, 
seems to be very variable. The forking of the veins of the mem- 
brane also varies much, some specimens having two veins dis- 
tinctly forked at the tip while other specimens do not show this 
character. 
However, with all its variation, this species is most easily 
recognized of all our Cydninae by its uniform bluish-black color 
