I find the necessary documents in the fine work of M. E. Blanchard (Annales des Sciences Naturelles, 3me série, tome v.) on the nervous system of Coleoptera. There I find that this centralisation of nerve power belongs especially to the Scarabæus, but most of these are too large; the Cerceris could neither attack nor carry them away; besides, many live in filth, where the cleanly Hymenopteron could not go to seek them. Motive centres very close together are also found among the Histers, which live on impurity, amid the smell of decay, and again that will not do; also in the Scolytus, which is too small, and finally in Buprestids and Weevils. What unexpected light amid the pristine obscurities of the problem! Amid the immense number of the Coleoptera which the Cerceris seem able to prey upon, two groups alone, Weevils and Buprestids, fulfil the indispensable conditions. They live far from decay and dung, which perhaps cause invincible repugnance in this dainty Cerceris; they are of most varied size, proportioned to that of their different captors, which may thus choose according to their convenience. They are far more vulnerable than all the others at the one point where the sting of the Hymenopteron can penetrate successfully, for at that point, all easily accessible to the dart, crowd the motor centres of feet and wings. At this point the three thoracic ganglia of Weevils lie very close, the hind two are contiguous. At that same spot in the Buprestids the second and third are welded in one large mass a little distance from the first. And as it is precisely Buprestids and Weevils which are hunted, to the absolute exclusion of all other game, by the eight species of Cerceris, whose food stores of Coleoptera have been ascertained, a certain internal likeness, namely, in centralisation of the nervous system must be the explanation why there are heaped in the dens of various Cerceris victims, outwardly so unlike.