310 The Ohio Naturalist. [Vol. Ill, No. 1, 



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 (i8) and third (i8) 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 tlie coxa be 

 removed it will be seen to extend across the body as a narrow 



