Opposite the shark-tooth sword is an object which might almost be taken for a similar weapon, but is, in fact, nothing but a common grass-blade, such as may be found in any of our lanes. I suppose that most of my readers must at some time have cut their fingers with grass, and the reason why is shown in the illustration, which represents a much-magnified blade of grass. The edges of the leaf are armed with sharp teeth of flint, set exactly like those of the sword, with their points directed towards the tip of the blade. The whole of the under surface of the blade is thickly set with similar but smaller teeth, arranged in the same manner. I have just brought a blade of grass from a lane near my house, and when it was placed under the half-inch power of the microscope, the resemblance to the sword was absolutely startling to some spectators who came to look at it. As if to make the resemblance closer, many savage weapons are edged with flat stones, flint chips, or pieces of obsidian, so that the flint teeth of the grass are exactly copied by the flint edgings of the sword. The old Mexican swords were nearly all edged with obsidian, as is seen in the lower right-hand figure of the next illustration. I possess a number of obsidian flakes which were intended for that purpose, but do not appear to have been used. The second figure from the top represents the head of a spear similarly armed, and I possess a small Australian implement in which the flakes of obsidian are set only on one side, so that the instrument can be used as a rude saw. Between these two weapons is a spear-head armed with shark-teeth. I have a very remarkable weapon of this kind, made in Mangaia. It is eleven feet in length, and, besides being armed with a double row of sharks’ teeth nearly to the handle, it has three curved blades similarly armed, set at distances of about two feet, and projecting at right angles. Thus, if the foe were missed with the point of the spear, he would probably be wounded by one of the blades. [Illustration: SWORD-GRASS. LEECH JAW. SAW-FISH]. [Illustration: SPEARS AND SWORD ARMED WITH OBSIDIAN AND SHARKS’ TEETH.] The upper figure represents a weapon where the natural bone of the sting-ray has been used as the point. On the opposite side are seen three natural objects similarly armed. The uppermost is another species of sword-grass, like that which has already been described. Next comes a magnified view of one of the three cutting instruments of the leech, showing the serrated teeth set along its edge, by means of which it produces the sharply-cut wounds through which it sucks the blood.