In the course of a comprehensive study of insects frequenting dwellings, attention was early drawn to a very handsome little Collembolan, which occurs commonly in moist situations in houses in Washington. It may often be found on window-sills, especially if there is unusual moisture from the presence of window plants, or in bathrooms, and, in fact, whereever moist conditions prevail. This species is a very handsome one, and seems, from reference to the authorities, to be undescribed. From thé manner of its holding the head, bent downwards almost at right-angles to the thorax, it would seem to fall into the genus Lepidocyrtus, erected by Sir John Lubbock. In habit it has in Europe a close ally in Seira domestica, Nicolet, which, as its name implies, is a frequenter of houses, and is separated generically from Lepidocyrtus by rather unimportant characters.