The Ohio Naturalist. 
[Vol. Ill, No. 1 , 
310 
cubitus after leaving the plate, but bending forward comes almost 
into contact and then turns sharply to the anal margin of the 
wing. The second (18) and third (18) divisions of the anal 
veins are separated from the first by the articulation by which the 
anal margin of the wing is doubled under when the wing is at 
rest. There are two of these, the anterior being a well defined 
vein, while the posterior is simply a broad chitinized area. The ■ 
bases of these veins articulate with one of the movable sclerites at 
the base of the wing. 
THE DETACHED SCLERITES AT THE BASE OF THE WING. 
The most prominent of these detached sclerites is a strongly 
chitinized V-shaped (19) piece which is directed in and forward. 
The base of the V articulates with the antero-lateral edge of the 
scutellum. The anterior arm of the vein articulates at its ex- 
tremity with the end of the subcostal vein. The posterior arm 
articulates by its anterior border and its extremity with a large ir- 
regular slightly chitinized sclerite to be described next. This V- 
shaped sclerite consists of a narrow piece projecting from the 
lateral chitinized border of the scutum and scutellum. In moving 
the wing the V rolls foward and over the spine ; so that, if the 
spine is depressed and the V is pulled as described, the wing 
is elevated. 
The second large sclerite (20) lies between the posterior arm 
of the first and the end of the wing veins. The anterior half 
which articulates with the posterior arm of the first is depressed 
below the level of the posterior half which articulates with the anal 
vein. The anterior depressed portion articulates with the projec- 
tion from the plate which serves as the origin for the media and 
cubitus. 
A third small sclerite (21) lies in the membrane just pos- 
terior to the posterior arm of the V-shaped sclerite. It is well 
chitinized and triangular in shape. 
There is a fourth sclerite (22) lying ventral to the base of 
the wing in the membrane which connects the base of the wing 
with the dorsal surface of the epimeron. It is oval and slightly 
chitinized. 
A fifth sclerite (23) similar in shape to the fourth, lies just 
anterior to the base of the wing in the triangular membrane lying 
under the outer border of the metathoracic scutellum. 
THE ABDOMEN. 
There are seven sterna (1-7) in the abdomen, six of which 
are visible. The first (2) can be seen at the outer angle of the 
metathoracic coxal cavity as a small triangle; but if the coxa be 
removed it will be seen to extend across the body as a narrow 
