268 
SYSTEMATIC ARRANGEMENT. 
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. Rap- 
torial fore legs are formed nearly in the same manner 
as formerly described when speaking of the predace- 
ous Orthoptera. They exist in the aquatic genera 
( Hydrocorisce ), 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 Cimicidee, dilated in 
the male, and of the ordinary size in the female. The 
hinder tibiae 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 consider- 
able 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 four 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, how- 
ever, have three joints in all the tarsi. Belostoma 
and Notonecta have two, a number of rare occur- 
