Note to Vol. V. Pp. 545, 546: The development of _Encyrtus fuscicollis_ has now been studied by Marchal, who has discovered the existence of embryonic dissociation. The chain of embryos and the epithelial tube in which they are placed, are formed as follows: the _Encyrtus_ deposits an egg in the interior of the egg of the _Hyponomeuta_. This does not kill the egg of the Lepidopteron, but becomes included in the resulting caterpillar. The amnion of the Chalcid egg lengthens, and forms the epithelial tube; while the cells within it become dissociated in such a way as to give rise to a chain of embryos, instead of a single embryo.—_C.R. Ac. Paris_, cxxvi. 1898, p. 662, and translation in _Ann. Nat. Hist._ (7), ii. 1898, p. 28. {71}CHAPTER II HYMENOPTERA ACULEATA _CONTINUED_—DIVISION II. DIPLOPTERA OR WASPS— EUMENIDAE, SOLITARY TRUE WASPS—VESPIDAE, SOCIAL WASPS—MASARIDAE DIVISION II. DIPLOPTERA—WASPS. _Anterior wings longitudinally plicate in repose; the pronotum extending back, so as to form on each side an angle reposing on the tegula; the basal segments of the hind body not bearing nodes or scales; the hind tarsi formed for simple walking. The species either solitary or social in their habits; some existing in three forms, males, females, and workers._ [Illustration: Fig. 26—Upper aspect of pronotum and mesonotum of a wasp, _Eumenes coarctata_. _a_, Angle of pronotum; _b_, tegula; _c_, base of wing; _d_, mesonotum.] This division of Hymenoptera includes the true wasps, but not the fossorial wasps. The name applied to it has been suggested by the fact that the front wings become doubled in the long direction when at rest, so as to make them appear narrower than in most other Aculeata (Fig. 27). This character is unimportant in function so far as we know,[40] and it is not quite constant in the division, since some of the Masaridae do not exhibit it. The character reappears outside the Diploptera in the genus _Leucospis_—a member of the Chalcididae in the parasitic series of Hymenoptera—the species of which greatly resemble wasps in coloration. A better character is that furnished by the well-marked angle, {72}formed by the pronotum on the dorsal part (Fig. 26). By a glance at this part a Diplopterous Insect can always be readily distinguished. Three families are at present distinguished in the Diploptera, viz. Eumenidae, Vespidae and Masaridae. We anticipate that Eumenidae and Vespidae will ultimately be found to constitute but one family. FAM. 1. EUMENIDAE—SOLITARY TRUE WASPS. _Claws of the feet toothed or bifid; middle tibiae with only one spur at tip. Social assemblages are not formed, and there is no worker-caste, the duties of nest-construction, etc., being performed solely by the female._