It is probable that atrophied antennæ and an anogenital ring also exist, but both of these must be situated under, or close to, the marginal ring, and as this will not dissolve they cannot be made out. The feet are peculiar: the two anterior pairs are short, thick, and deformed, the joints much swollen, and the tibia and tarsus fused into one; the posterior pair are longer and more slender, and the joints can be separated. The rostrum is normal, the mentum probably dimerous. On the dorsum six round spots are visible in two rows, answering to the six depressions in the test. Epidermis much wrinkled. There are no clear spinneret-orifices, but towards the margin the skin is covered with great numbers of very minute puncta, which may be spinnerets, and also with rather large clear oval cells. If antennæ exist they must be extremely small. Larva and male unknown. Hab. In Japan, on Populus tremula, var. villosa. Specimens from Nikko, sent by Mr. Koebele (his No. 1492). When publishing in the Ent. Mo. Mag. my list of Mr. Koebele's collection I had not made up my mind as to this species, but I think it is undoubtedly a Sphœrococcus. In its hardness and resistance to potash it approaches Chœtococcus bambusœ, and in the unequal and deformed feet Sphœrococcus inflatipes. Genus Chætococcus, gen. nov. General characters of Idiococcinœ; anal ring bearing some hairs. Chætococcus bambusæ. Sphœrococcus bambusœ, Maskell, Trans. N.Z. Inst., 1892, vol. xxv., p. 237. Mr. E. E. Green drew my attention some months ago to the fact that this species has hairs on the anal ring. When originally describing it I had great difficulty in finding the ring at all, on account of the excessive hardness of the epidermis, which refused to become transparent even after very long boiling; but I find one of my prepared specimens, after five years' immersion in dammar solution, sufficiently lucid to show some long hairs, which, as far as I can make out, are six in number, though there may be eight. This species, originally from the Sandwich Islands, has since been found in Ceylon, and I hear lately from M. d'Emmerez de Charmoy that it is plentiful in Mauritius. But Mr. Green, in the same letter to me, made the somewhat startling statement that he was convinced that specimens in Ceylon “identical with Sphœrococcus bambusœ” were also identical with the genus Antonina, Signoret, a statement founded upon actual comparison with specimens of A. purpurea