There are numerous species belonging to this genus, all natives of tropical America. The only species said to be found within the limits of the United States occurs, if at all, in southern California. It is, however, probably only found in the lower peninsula of California, which is Mexican territory. No examples from Upper California are known to the writer. (1) =Mechanitis californica=, Reakirt, Plate VIII, Fig. 2, ♂ (The Californian Long-wing). The original description given by Reakirt in the "Proceedings of the Entomological Society of Philadelphia," vol. v, p. 223, is as follows: "Expanse, 2.45-2.56 inches. Fore wing above, brownish-black; a basal streak over the median nervure, and two rounded spots near the inner angle, orange-tawny; of these the outer is the largest, sometimes the inner is yellow, and sometimes both are nearly obsolete; a spot across the cell near its termination, much narrower than in _M. isthmia_, and in one example reduced to a mere dot on the median nervure; a more or less interrupted belt across the wing from the costa to near the middle of the outer margin, and an oblong subapical spot, yellow; in the specimen just mentioned there is an additional yellow spot below the medio-central veinlet. "Beneath the same, suffused with orange-tawny at the base and the inner angle, with a row of eight or nine submarginal white spots along the outer margin. "Hind wing above, orange-tawny, with a broad mesial band, entire, and a narrow outer border, from the middle of the costa to the anal angle, brownish-black. "Beneath the same, a yellow spot on the root of the wing; a band runs along the subcostal nervure from the base to the margin, where it is somewhat dilated; immediately below its termination, a mark in the form of an irregular figure 2, usually with the upper part inordinately enlarged; between this and the base, on the central line of the band above, three small subtriangular spots; all these markings blackish-brown; a submarginal row of seven white spots on the outer margin. "Body brownish; wing-lappets and thorax spotted with tawny-orange; antennæ yellowish, with the base dusky. "_Hab._--Los Angeles, California." The species is probably only a local race of the insect known to naturalists as _M. polymnia_, Linnæus, as Reakirt himself admits. The figure in the plate is from one of Reakirt's paratypes. Genus CERATINIA, Fabricius _Butterfly._--Butterflies of medium size, very closely related in structure to the butterflies of the genus _Mechanitis_. The peculiarity of this genus, by which it may be distinguished from others belonging to this subfamily, is the fact that the _lower_ discocellular vein in the hind wing of the male sex is strongly in angled, while in the genus _Mechanitis_ it is the _middle_ discocellular vein of the hind wing which is bent inwardly. _Early Stages._--Unknown for the most part.