. Bulletin - United States National Museum. Science. SYNOPSIS OF NORTH AMERICAN SYRPHIDiE. 289 /Ve^—Coraposed of the five joints of the tarsi, the basal one of which is called the metatarsus, the distal one terminating in two clatvs or ungues, on the under side of each of which is a small membranous ai)pendage, the pulvillus. WINGS. Horders or margins, anterior, exterior, and posterior of the wing, directed transversely. Aliilet.—The lobe or flap of the wing, without veins, on the basal posterior part. Venation.—Costal vein, the one bordering the anterior margin of the wing; auxiliary, nearly
. Bulletin - United States National Museum. Science. SYNOPSIS OF NORTH AMERICAN SYRPHIDiE. 289 /Ve^—Coraposed of the five joints of the tarsi, the basal one of which is called the metatarsus, the distal one terminating in two clatvs or ungues, on the under side of each of which is a small membranous ai)pendage, the pulvillus. WINGS. Horders or margins, anterior, exterior, and posterior of the wing, directed transversely. Aliilet.—The lobe or flap of the wing, without veins, on the basal posterior part. Venation.—Costal vein, the one bordering the anterior margin of the wing; auxiliary, nearly parallel with the eosta from the base, and terminating in that vein near its middle; connected towards its base with the costa by a transverse cross vein, the humeral cross-vein; the first longitudinal vein arises from the auxiliary-vein in the vicinity of the humeral cross-vein, follows the auxiliary subparallel, and is inserted in the costa; the second longitudinal vein arises from the first longitudinal a little beyond the humeral cross-vein, follows the former, and is inserted in the costa, or some- times in the first vein before its tip ; the third longitudinal arises by a fork from the second longitudinal, a little distance before the termination of the auxiliary, and is inserted in the costa at its tip; in its course it gives off a short branch, the anterior or small cross-vein, to connect with the fourth longitudinal vein ; fourth longitudinal vein arises from the second main vein-stem opposite the humeral cross-vein and terminates in the third longitudinal a short distance before its tip; it gives off, first the anterior basal cross-vein behind, opposite the origin of the third vein, second the anterior cross-vein to connect with the third longitudinal, and, just before it bends forward to connect with the third vein, it receives the posterior cross-vein; ihe fifth longitudinal vein arises near the origin of the fourth and terminates a little before the posterior
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