This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 edition. Excerpt: ...the hind wings of moths where an extreme cephalization of flight has been arrived at, show a less specialization of the scale-covering than is shown by the hind wings of moths whose flight-function is not so excessively cephalized. Which, indeed, is to be expected, because of the lesser importance of the hind wings in cases of extreme cephalization of flight. This is well shown within the limits of a single family in the case of Calyasymbolas myops, a Sphingid with the hind wings large in comparison with the hind wings of Chcerocampa, Philampelus, Ellema.and others showing extreme cephalization of flight. In Calyasymbolas the disk of the hind wing is uniformly covered with flat scales, only the basal third of the wing showing long, weak scale-hairs. In Philampelus achemon only the marginal brown edging is composed of specialized scales, without thepresence of scale-hairs, while all the discal and basal portion of the wing is covered with long, rather thickened scale-hairs, in addition to flat scales. Chcerocampa tersa shows a similar condition, as also does Ellema bombycoides. The fact that a heavy flyer shows a less specialized scale-covering than a swift flyer is also illustrated among the Sphingidae. Triptogon modesta, a slow, heavy-bodied moth compared with Philampelus, has its forewings covered with long, thickened, two-to three-pointed, rather flattened scale-hairs thickly inserted, but rather assurgent, and not closely appressed to the wing-surface. The hindwings bear elongate, single-pointed scale-hairs, and also some scales like those of the forewing; altogether a much more generalized condition of scale development than that of Philampelus, whose forewings are uniformly covered with broad three-to seven-pointed flat scales, .