Of smaller size and clad in black with trimmings of silvery down on the edge of the abdominal segments, the Tarsal Tachytes frequents the ledges of soft limestone in fairly populous colonies. (T. tarsina, LEP.) (According to M. J. Perez, to whom I submitted the Wasp of which I am about to speak, this Tachytes might well be a new species, if it is not Lepelletier's T. tarsina or its equivalent, Panzer's T. unicolor. Any one wishing to clear up this point will always recognize the quarrelsome insect by its behaviour. A minute description seems useless to me in the type of investigation which I am pursuing.--Author's Note.) August and September are the season of her labours. Her burrows, very close to one another when an easily-worked vein presents itself, afford an ample harvest of cocoons once the site is discovered. In a certain gravel-pit in the neighbourhood, with vertical walls visited by the sun, I have been able within a short space of time to collect enough to fill the hollow of my hand completely. They differ from the cocoons of the preceding species only in their smaller size. The provisions consist of young Acridians, varying from about a quarter to half an inch in length. The adult insect does not appear in the assorted bags of game, being no doubt too tough for the feeble grub. All the carcases consist of Locust-larvae, whose budding wings leave the back uncovered and put one in mind of the short skirts of a skimpy jacket. Small so that it may be tender, the game is numerous so that it may suffice all needs. I count from two to four carcases to a cell. When the time comes we will discover the reason for these differences in the rations served.