The beautiful little Butterflies included by Fabricius in this genus, are scattered over all parts of the world, but are most numerous within the tropics, and particularly in South America, for in Brazil alone I collected near 120 species. They are an obvious and very natural family, though the species are as yet but little understood, and not one half of them described. I have observed a singular peculiarity in a great many of these insects, which is, that when they are at rest in the sun, the lower wings are constantly in a quick vibrating motion up and down, as if the insect was rubbing them together, more particularly where the two lobes (or obtuse tails) of the under wings meet, though what purpose this is intended to accomplish remains unknown. The upper surface of the wings in the greatest number of the _Hair streaks_ (as they are aptly called by English collectors) are of various shades of vivid blue, so that the species can only be ascertained from the under markings, which are usually very striking and delicate: they are all of a small size. This is an African species, and both sexes are in the cabinet of my friend Mr. Haworth. * * * * * Pl. 70 [Illustration] CONUS terebra, _Screw Cone._ * * * * * GENERIC CHARACTER.--See Pl. 65. * * * * * SPECIFIC CHARACTER. _C. cylindraceo-elongatus, albidus, striis transversis elevatis, fasciisque binis flavescentibus, spira crassa obtusa._ Lam. Cylindric elongated; whitish, with two yellowish bands, and transverse elevated striae; spire thick, obtuse. Conus Terebellum. _Gmelin_, p. 3390. 44. (omitting the varieties). _Martini_ 2. _tab._ 52. _fig._ 577. _Seba_, 42. _fig._ 13. (uncoated). _Ency. Meth._ 339. _fig._ 1. Conus Terebra. _Lamarck._ _Annal. du Mus._ vol. xv. p. 427. _no._ 144. _Var._ A, without bands. _Ency. Methodique_, 339. _fig._ 2. * * * * * Though this is not an uncommon Shell, it is rarely seen so large as that now represented from the cabinet of Mrs. Bolton of Storrs. Of this extensive genus Lamarck has written a valuable account in the Annals of the French Museum, where he has rightly pointed out the mistake of Gmelin in placing as varieties of this species, one or two other very distinct shells: the colour of the bands is not always certain, for I have seen specimens in which they were of a dark brown; but the very thick spire, and slender form of the body whirl, with the distant, regular, and greatly elevated striae, render it a species not easily mistaken, though in general form it comes very near to _C. nussatella_, and two or three others; the spiral volutions are deeply concave, and the tip and base tinged with violet. It is a native of the Indian seas. * * * * * Pl. 71 [Illustration] STROMBUS mutabilis, _Little pink-mouthed Strombus._