The notes which are herein included, as to “parthenogenesis” and to the power of “gall-” making, will not, it is hoped, be considered either trivial or unnecessary. In both cases remarks of a vague and general character may be found in various works dealing with Coccids: but my intention has been to bring the subjects forward more particularly and definitely. It is to be hoped that in time the problems connected with these matters may be attacked systematically; and that European entomologists, when they get tired of the already dreadfully-worn grooves of the Lepidoptera and Coleoptera, will find the Coccids worthy of their best attention. It has occurred to me that a few words may usefully be said about the mode of investigating systematically the species and varieties of Coccids. In common with everything else, of course, the outward appearance and habits of these insects, their position on bark or leaves, their colour and size and general form, must be carefully noted. But this exterior study, of itself, would be of extremely little use to the student, and indeed would lead him to utter confusion in a very short time: not only could he seldom distinguish between species and genera, but he would frequently confound Coccids with Lecanids, and I have seen species of Australian Psyllids which in outward appearance in the pupal stage very closely indeed resemble Diaspids. Close examination of the anatomical characters of the insects is therefore necessary: but here again the student will find himself in a difficulty unless proceeding in the proper way. The female insects, which are in most cases the most important, are frequently so covered with cotton or meal that the organs cannot be made out without treatment with reagents: moreover, at gestation they almost always shrivel up into such small, shapeless masses that their true form is often entirely lost. A student must therefore examine them, and preserve them for comparison, in two ways:—the specimen cabinet should contain as many, in their natural position if possible on portions of their food-plant, as form a typical collection; and, besides, others should be mounted for microscopical study, either whole or as dissected parts. The plan which I have found best adapted for these mounted specimens is as follows: it involves several operations, which, however, do not occupy as much time as might be thought from their description. First, after thoroughly investigating the natural exterior form, colour, position, &c., of the insect, select as many individuals as may be required for dissection and mounting, and, if they are encased in thick cottony sacs, or in thick wax, or under puparia, carefully extract them therefrom—a proceeding which will become less difficult with practice. Secondly, boil