FAMILY OYNIPIDJE. 147 



In descriptive Hymenopterology it is the median seg- 

 ment which is the more important of the two ; for it 

 is that which bears the arese, reticulations, and keels so 

 important ormisologically in the Ichneumonidsd and 

 other groups. In this work I have used the term 

 " median segment " to mean the fourth thoracic seg- 

 ment, and as practically equivalent to the metathorax 

 of other writers, e. g. Thomson and Foerster. It is 

 frequently covered with woolly hair, especially in the 

 parasitic species. 



The legs are moderate in size, sometimes the hinder 

 legs are rather elongate (e. g. JEgilips) . The trochanters 

 are biarticulate ; the fore tibige bear one or two spurs, 

 the hind pair two unequal spurs. The tarsi are five- 

 jointed. As a rule the metatarsus is as long as the 

 succeeding three joints united. The claws are simple 

 as in Cynips, or cleft as in some species of Andricus 

 and Neuroterus. The patellae are seldom prominent. 



The ovipositor. This in its morphological structure 

 agrees quite with the rest of the Hymenoptera, although 

 exhibiting some peculiar features. It occupies the 

 entire length of the abdomen, and in some species is 

 nearly as broad as it. Looking at it as it lies in the 

 abdomen, we find a broad chitinous plate (the oblong 

 plate of the Tenthredinidse, see Yol. I, PL X, fig. 5), 

 which is divided into an anterior or upper, and a pos- 

 terior or lower part, in addition to the small triangular 

 plate. At the base it forms a semicircle, or at least 

 is broadly rounded. The anterior part is attached to 

 the lower end of the triangular plate (PI. Y, fig. 15d), 

 and more or less firmly to the base of the posterior. 

 It becomes narrowed towards the apex, but before the 

 apex there is frequently a rounded projection ; and on 

 the opposite side of the apex there is a papilla-like body 

 (the anal papilla, figs. 15 / and j). Broad at the base, 

 the posterior piece becomes narrower from the basal 

 third or so, but the apical fourth or more of it in some 

 species is broader and distinctly separated from the basal 

 part, it representing the sheath (Yol. I, PI. X, fig. 5) of 



