=Lee, A. Bolles.= Les balanciers des Diptères, leurs organes sensifères et leurs histologie. (Recueil Zool. Suisse, i, 1885, pp. 363–392, 1 Pl.) =Poppius, Alfred.= Ueber das Flügelgeäder der finnischen Dendrometriden. 1 Taf. (Berl. Entom. Zeitschr., 1888, pp. 17–28.) =Comstock, J. H.= On the homologies of the wing-veins of insects. (American Naturalist, xxi, 1887, pp. 932–934.) =Brauer, F.= Ansichten über die paläozoischen Insekten und deren Deutung. (Annal. d. k. k. naturhist. Mus. Wien, Bd. i, 1886, pp. 86–126, 2 Taf.) =Brauer, F., und J. Redtenbacher.= Ein Beitrag zur Entwicklung des Flügelgeäders der Insekten. (Zool. Anz. 1888, pp. 443–447.) =Redtenbacher, J.= Vergleichende Studien über das Flügelgeäder der Insekten. 12 Taf. (Annalen d. k. k. naturhist. Hofmuseums zu Wien, 1886, i, pp. 153–231.) =Schoch, G.= Miscellanea entomologica. I. Das Geäder des Insektenflügels; II. Prolegomena zur Fauna dipterorum Helvetiae, Wissenschaftl. (Beilage z. Programm d. Kantonsschule Zurich, 1889, 4º, 40 p.) =Bondsdorff, A.= von. Ueber die Ableitung der Skulpturverhältnisse bei den Deckflügeln der Coleopteren. (Zool. Anz., 1890, xiii Jahrg., pp. 342–346.) =Spuler, Arnold.= Zur Phylogenie und Ontogenie des Flügelgeäders der Schmetterlinge. (Zeitschr. wissens. Zool., liii, 597–646, 2 Taf., 1892.) Also the writings of Adolph, Bugnion, Calvert, Comstock, Diez, Giraud, Gonin, Graber, Kellogg, Packard, Pratt, Scudder, Walsh. _g._ Mechanism of flight =Marey’s views on the flight of insects.=—As we owe more to Marey than to any one else for what exact knowledge we have of the theory of flight of insects, the following account is condensed from his work entitled “Movement.” The exceedingly complicated movements of the wings would lead us, he says, to suppose that there exists in insects a very complex set of muscles of flight, but in reality, he claims, there are only the two elevator and depressor muscles of each wing.[34] And Marey says that when we examine more closely the mechanical conditions of the flight of insects, we see that an upward and downward motion given by the muscles is sufficient to produce all these successive acts, so well coordinated with each other; the resistance of the air effecting all the other movements. He also refers to the experiments of Giraud which prove that the insect needs for flight a rigid main-rib and a flexible membrane. [Illustration: FIG. 163.—The two upper lines are produced by the contacts of a drone’s wing on a smoked cylinder. In the middle are recorded the vibrations of a tuning-fork (250 vibrations per second) for comparison with the frequency of the wing movements. Below are seen the movements of the wing of a bee.—After Marey. ]