in this respect of the perfect Chrysididae from other Petiolata is due to a greater number of the terminal segments being indrawn so as to form the tube, or telescope-like structure from which the series obtains its name. This tube is shown partially extruded in Fig. 1; when fully thrust out it is seen to be segmented, and three or four segments may be distinguished. The ovipositor proper is concealed within this tube; it appears to be of the nature of an imperfect sting; there being a very sharply pointed style, and a pair of enveloping sheaths; the style really consists of a trough-like plate and two fine rods or spiculae. There are no poison glands, except in _Cleptes_, which form appears to come very near to the Aculeate series. Some of the Chrysididae on occasions use the ovipositor as a sting, though it is only capable of inflicting a very minute and almost innocuous wound. [Illustration: Fig. 1.—_Chrysis ignita_, ♀. England.] Although none of the Ruby-flies attain a large size, they are usually very conspicuous on account of their gaudy or brilliant colours. They are amongst the most restless and rapid of Insects; {3}they love the hot sunshine, and are difficult of capture. Though not anywhere numerous in species, they are found in most parts of the world. In Britain we have about twenty species. They usually frequent old wood or masonry, in which the nests of Aculeate Hymenoptera exist, or fly rapidly to and fro about the banks of earth where bees nest. Dr. Chapman has observed the habits of some of our British species.[2] He noticed _Chrysis ignita_ flying about the cell of _Odynerus parietum_, a solitary wasp that provisions its nest with caterpillars; in this cell the _Chrysis_ deposited an egg, and in less than an hour the wasp had sealed the cell. Two days afterwards this was opened and was found to contain a larva of _Chrysis_ a quarter of an inch long, as well as the Lepidopterous larvae stored up by the wasp, but there was no trace of egg or young of the wasp. Six days after the egg was laid the _Chrysis_ had eaten all the food and was full-grown, having moulted three or four times. Afterwards it formed a cocoon in which to complete its metamorphosis. It is, however, more usual for the species of _Chrysis_ to live on the larva of the wasp and not on the food; indeed, it has recently been positively stated that _Chrysis_ never eats the food in the wasp's cell, but there is no ground whatever for rejecting the evidence of so careful an observer as Dr. Chapman. According to M. du Buysson the larva of _Chrysis_ will not eat the lepidopterous larvae, but will die in their midst if the _Odynerus_ larva does not develop; but this observation probably relates only to such species as habitually live on _Odynerus_ itself. The mother-wasp of _Chrysis bidentata_ searches for a cell of _Odynerus spinipes_ that has not been properly closed, and that contains a full-grown larva of that wasp enclosed in its cocoon. Having succeeded in