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268 proportions and in the amount of the component articulations. In some the legs are nearly equal, in others the hinder pair have the thighs very much lengthened, thickened, and armed with spines. Raptorial fore legs are formed nearly in the same manner as formerly described when speaking of the predaceous Orthoptera. They exist in the aquatic genera (Hydrocorisæ), and also in some terrestrial kinds, such as the Syrtes, in which they terminate in a monodactyle claw like those of some of the Crustacea. The thighs sometimes serve to distinguish the sexes, being, in many species of the Cimicidæ, dilated in the male, and of the ordinary size in the female. The hinder tibiæ sometimes present the peculiarity of being furnished with very broad foliaceous expansions, irregularly toothed on the edge; in some instances as wide as the body, and strongly contrasting with it by being of an entirely different colour. Such broad surfaces exposed to the air must exercise considerable influence on flight, and are probably of service in balancing the body. The number of joints in the tarsi varies from one to five, but when the latter amount occurs it is not in all the tarsi, there being no example of a strictly pentamerous species in this order. Several kinds are heteromerous, that is, having four joints in each of the foir anterior tarsi, and five in the posterior pair. In Ranatra the number of joints may be represented by 2, 1, 1; and in Sigara and Naucoris, by 1, 2, 2. The great majority, however, have three joints in all the tarsi. Belostoma and Notonecta have two, a number of rare