268 SYSTEMATIC ARRANGEMENT. 



proportions and in the amount of the componen 

 articulations. In some the legs are nearly equal, ii 

 others the hinder pair have the thighs very mu'cl 

 lengthened, thickened, and armed with spines. Rap- 

 torial fore legs are formed nearly in the same marine: 

 as formerly described when speaking of the predace- 

 ous Orthoptera. They exist in the aquatic genen 

 (Hydrocorisce), and also in some terrestrial kinds 

 such as the Syrtes, in which they terminate in j 

 monodactyle claw like those of some of the Crustacea 

 The thighs sometimes serve to distinguish the sexes 

 being, in many species of the Cimicidae, dilated ii 

 the male, and of the ordinary size in the female. Th< 

 hinder tibiae sometimes present the peculiarity o 

 being furnished with very broad foliaceous expansions 

 irregularly toothed on the edge; in some instance: 

 as wide as the body, and strongly contrasting with i 

 by being of an entirely different colour. Such broac 

 surfaces exposed to the air must exercise consider 

 able influence on flight, and are probably of servic< 

 in balancing the body. The number of joints in th< 

 tarsi varies from one to five, but when the latte: 

 amount occurs it is not in all the tarsi, there bein< 

 no example of a strictly pentamerous species in thii 

 order. Several kinds are heteromerous, that is, having 

 four joints in each of the ftfur anterior tarsi, and five 

 in the posterior pair. In Ranatra the number o 

 joints may be represented by 2, 1, 1 ; and in Sigan 

 arid Naucoris, by 1, 2, 2. The great majority, how- 

 ever, have three joints in all the tarsi. Belostonu 

 and Notonecta have two, a number of rare occi 



