These are among the smallest insects, for the largest does not measure more than ⅓ of an inch in length, and most of them are very much smaller. They are chiefly found in damp situations among loose soil, decaying vegetable matter, and such like material, and can stand a very cold temperature. They are easily distinguished from the silver-fish by the few joints in the antennae, and the great powers of jumping they possess by means of their long jointed tail appendages. Our common species, _Lipura sp._, is at times very abundant in the loose soil; after a sudden thunderstorm they are often washed out in such numbers that, carried into the little pools along the road side, they form a dull blue scum on the surface of the water. They measure ⅓ of a line in length; are of a dull blue colour, and have short, thickened antennae and legs; the body is distinctly segmented and rounded at the tip. Resting on the surface of the water they are constantly in motion, springing up every moment like little rubber balls. Another species belonging to the Genus _Smynthurus_, allied to _S. viridis_, a European form, but probably an undescribed native species, appeared in great numbers in lucerne paddocks in S. Australia in 1896, where they did a great deal of damage by eating the surface of the leaves, swarming over the fields in countless millions. It is a member of this genus (_Smynthurus lutus_) that Lubbock has described in such an entertaining manner when recounting the courtship of these queer little creatures. Family 2. Silver-fish. THYSANURA. The silver-fish are divided into two distinct groups: those clothed with fine loose silver-like scales, and those in which the scales are absent and are replaced by fine hairs. The abdomen contains ten segments; their bodies are elongated, furnished with long, slender, many jointed antennae tapering to the extremities, and the tip of the abdomen carries two or three slender thread-like tail appendages. Though the group has been divided into four divisions, there are not many species described; they frequent warm, dry, dark situations. [Illustration: =Fig. 1.=--_Lepisma saccharina_ (Linn.). The common Silver-Fish. (Redrawn from Marlatt’s “Household Insects.”)] _Lepisma saccharina_, the Common European Silver-fish, measures up to ½ an inch in length, and is covered with delicate lead-coloured scales that give it a dull metallic lustre. They are great pests in libraries, where they eat the glaze on papers or clothbound books, pasted labels, or even the surface of etchings and engravings. Our common species was generally supposed to be this insect; but Dr. Silvestri, to whom I submitted a number of specimens caught in Sydney houses, says that it is _Lepisma longicaudata_, the common African species unknown in Europe.