Sometimes the Skip-jack is made of a fowl’s merrythought, as shown in the illustration; sometimes of the breast-bone of a goose; and sometimes of a piece of wood cut into the semblance of a frog, and painted. In all cases, however, the machinery is practically the same. I may mention _en passant_ that these frog Skip-jacks are most acceptable presents to savage chiefs in many parts of the world, and that the most powerful and venerable warriors are as delighted with these toys as any European child of six years old. * * * * * NOW we will turn to Nature, and see what she has in the way of Skip-jacks. All entomologists will at once have before their minds the vast groups of Skip-jack Beetles, technically termed _Elateridæ_, and also known as Click-beetles, from the sharp clicking sound which they produce when in the execution of their curious gymnastics. To this group belong the fire-flies of warm countries, and it may be mentioned that the larvæ of some of our species are too familiar to the agriculturist under the name “wireworm.” [Illustration: SKIP-JACK BEETLE. GRASSHOPPER.] [Illustration: SKIP-JACK.] All these beetles have very short legs and very long bodies, so that if they should fall on their backs on a smooth surface, they could not recover themselves. Now, as they, when discovered, instinctively try to save themselves by falling to the ground, it is evident that some means must be used to enable them to regain their position. This is found in a most curious apparatus. Attached to the “prothorax” is a rather long, pointed, and very elastic projection exactly corresponding with the tongue of the Skip-jack. The end of this tongue fits into a groove in the “sternum.” When the beetle falls on its back, it curves its body as shown in the illustration, the tongue thus being freed from its groove. It then smartly springs the tongue back into its place with the sharp clicking sound already referred to, and does so with such force that it leaps into the air to some height. Generally it falls on its feet, but if it should fail, it repeats the process. If one of these beetles be laid on a plate or similar smooth surface, it will skip ten or twelve times without stopping, and after a short rest will begin again. * * * * * THERE are some curious little beings, popularly called Spring-tails, which afford excellent examples of the Leaping Spring. Their exact place in the system of Nature is rather uncertain, some zoologists considering them as insects, while strict entomologists reject them. They are very small, and mostly of a darkish brown colour.