first stab of the lancet in front; a considerable movement to the rear, measuring about two-fifths of an inch; lastly, two lancet-thrusts at two points very close together. Thus speaks the science of man; thus counsels reason, guided by anatomical structure. Having said this much let us observe the insect's practice. There is no difficulty about seeing the Tachytes operate in our presence; we have only to resort to the method of substitution, which has already done me so much service, that is, to deprive the huntress of her prey and at once to give her, in exchange, a living Mantis of about the same size. This substitution is impracticable with the majority of the Tachytes, who reach the threshold of their dwelling in a single flight and at once vanish underground with their game. A few of them, from time to time, harassed perhaps by their burden, chance to alight at a short distance from their burrow, or even drop their prey. I profit by these rare occasions to witness the tragedy. The dispossessed Wasp recognizes instantly, from the proud bearing of the substituted Mantis, that she is no longer embracing and carrying off an inoffensive carcase. Her hovering, hitherto silent, develops a buzz, perhaps to overawe the victim; her flight becomes an extremely rapid oscillation, always behind the quarry. It is as who should say the quick movement of a pendulum swinging without a wire to hang from. The Mantis, however, lifts herself boldly upon her four hind-legs; she raises the fore-part of her body, opens, closes and again opens her shears and presents them threateningly at the enemy; using a privilege which no other insect shares, she turns her head this way and that, as we do when we look over our shoulders; she faces her assailant, ready to strike a return blow wheresoever the attack may come. It is the first time that I have witnessed such defensive daring. What will be the outcome of it all? The Wasp continues to oscillate behind the Mantis, in order to avoid the formidable grappling-engine; then, suddenly, when she judges that the other is baffled by the rapidity of her manoeuvres, she hurls herself upon the insect's back, seizes its neck with her mandibles, winds her legs round its thorax and hastily delivers a first thrust of the sting, to the front, at the root of the lethal legs. Complete success! The deadly shears fall powerless. The operator then lets herself slip as she might slide down a pole, retreats along the Mantis' back and, going a trifle lower, less than a finger's breadth, she stops and paralyses, this time without hurrying herself, the two pairs of hind-legs. It is done: the patient lies motionless; only the tarsi quiver, twitching in their last convulsions. The sacrificer brushes her wings for a moment and polishes her antennae by passing them through her mouth, an habitual sign of tranquillity returning after the emotions of the conflict; she seizes the game by the neck, takes it in her legs and flies away with it.