283 
No. 105.] 
diameter. It is of an ovate form, often conspicuously attenuated 
towards its tip, (as represented, fig. 1.) whence the two valvular sheaths 
of the ovipositor are seen more or less exserted, and sometimes the 
apex of the ovipositor itself projecting between them like a fine slen¬ 
der thread. According to Mr. Curtis, by a slight pressure on the 
abdomen of the living insect, the ovipositor (Plate fig. /) can be 
made to protrude, and may then be drawn out to nearly thrice the 
length of the body. 
The wings are hyaline and colorless, appearing like thin plates 
of glass or mica, but reflecting the tints of the rainbow, particularly 
the violet, when viewed in certain directions. Their margins are 
densely ciliated with longish hairs, and their surface is covered with 
minute pubescence. The mediastinal or submarginal nerve is but 
slightly distant from the costal (marginal), and becomes confluent 
with it rather forward of the middle of the exterior margin. From 
its middle, it sends a small connecting nerve backward to the post- 
costal. The postcostal, which is the most conspicuous nervure of 
the wing, runs direct, or with but an insensible curve, to the tip of 
the wing. The medial is straight, and attains the inner margin at 
about three-fourths of the distance from the base to the apex of the 
wing. The anal runs nearly parallel with the inner margin, and, with 
a very sudden curve from its direct course, joins the margin near 
its middle. It gives off an obscure branch at its angle, which curves 
outwards and backwards, joining the medial, or rather, seeming (if 
the wing be moved so as to give a slightly different incidence to the 
light) to be continued onward, parallel with and contiguous to the 
medial nerve, till it attains the margin of the wing. The medial and 
anal nerves are very slender, and are often invisible, except in a par¬ 
ticular reflection of the light. The former, especially, can seldom be 
distinctly traced, except towards its termination. These details of the 
neuration of the wing apply equally well to all the species of Ceci- 
domyia that have fallen under my observation, save only that they 
are more distinctly traced in the others, particularly the larger species. 
At rest (Plate fig. 6,) the wings are laid one upon the other, 
reposing horizontally upon the back of the abdomen, and reaching 
about a fourth of their length beyond it. 
The legs are whitish or very pale yellow, long and slender, of a 
cylindrical form, and of nearly the same diameter through their entire 
