The culminating feature in the biography of any hunting insect is the method of attack; and so I did my utmost to observe the Pelopæus at grips with her quarry. My patient waits in front of her favourite hunting-grounds, old walls and bramble-thickets, were not crowned with any great success. I have seen the Pelopæus fall suddenly upon the Spider madly fleeing and clasp and carry off her victim almost without delaying her flight. The other game-hunters alight on the ground, solemnly make their fastidious preparations and distribute their lancet-strokes with the calm deliberation which a delicate operation demands. The Pelopæus darts forward, seizes her prey and makes off, very much as the Bembeces do. There is reason to believe, so sudden is the rape, that she makes use of her sting and her mandibles only during the flight, on her journey home. This fierce procedure, which is incompatible with scientific surgery, explains even better than the narrowness of the cells her preference for Spiders of small dimensions. A sturdy prey, armed with its two poison-fangs, would constitute a deadly peril to the ravisher disdainful of precautions. The lack of artifice calls for a feeble victim. It also makes us suspect that the Spider so hastily set upon is killed. Indeed, I have over and over again armed my eyes with a magnifying-glass and scrutinized the contents of cells whose eggs had not yet hatched, a proof that the provisions were of recent date: there is never a quiver of either palpi or tarsi in the victims stored away. It is only with difficulty that I manage to preserve them: in ten days’ time, more or less, I see them grow mouldy and putrefy. The Spiders, therefore, are dead, or very nearly so, when they are potted by the Pelopæus. Is the skilful paralysis which the Calicurgus practises upon the Tarantula, who keeps fresh for seven weeks, unknown to the Pelopæus, or is it impracticable in the fierceness of the attack? Are we, in her case, dealing not with a delicate practitioner, who is able to abolish movement without destroying life, but rather with a brutal sacrificer, who, to deprive her victims of their power of movement, kills them? Everything in their withered aspect and their rapid decay assures us that this is so. The evidence does not surprise me: we shall see, as we go on, other victimarii inflict death instantly with a stroke of the stiletto, delivered with a science of slaughter no less astonishing than the science of the paralysers. We shall see the reasons that call for these complete murders and we shall recognize, under other aspects, the profound anatomical and physiological knowledge which a rational action would demand in order to rival the unconscious action of instinct. As for the necessity of killing her Spiders under which the Pelopæus labours, I find it impossible even to suspect the cause.