596 



ARTHROPODA. 



for the bristle-shaped, styliform mandibles and maxilla. Eyes com- 

 pound, usually with ocelli as well. Two pairs of wings in most : 

 sometimes wanting. Pupa generally active. 



The recent Rhynchota are of very varied habit, and they may be 

 divided into two principal sections in accordance with the structure 

 of the wings. In one great section of the order (Homoptera) the 

 anterior and posterior wings are both membranous, the former being 

 simply of firmer texture than the latter. To this section belong 

 such existing types as the Aphides, the Cicadas (fig. 447, c), the 

 Lantern-flies, &c. In the other great section of the order {Heter- 

 optera) the anterior wings are hardened at their bases by chitine and 

 remain membranous towards their apices (fig. 447, b), constituting 



Fig. 447. — Recent Rhynchota. a, ThriJ>s, enlarged ; B, Nefia cinerea, enlarged ; c, Cicada 

 Anglica, the wings on the right side of the body being omitted ; d, Larva of the same ; e, Pupa 

 of the same. (Figs, c, D, and E are after Westwood.) 



protective cases (" hemelytra") for the wholly membranous hind 

 wings. In this section are included the numerous forms of Land- 

 bugs and Water-bugs. 



As regards their geological distribution, the place of the Rhynchota 

 in the Palaeozoic rocks is taken by the Hemipteroid forms of the 

 PalcEodictyoptera. In the Jurassic rocks, however, appear for the 

 first time well-marked representatives of both the above-mentioned 

 sections of the order ; the Homopterous forms being represented by 

 types allied to the Cicadas, while the Heteropterous division is 

 represented by forms closely allied to, or identical with, the existing 

 Water-scorpions (Nepd) and the Land-bugs. The little Plant-lice 

 {Aphis, &c.) appear in the Cretaceous rocks (Wealden) ; and a vast 

 number of Tertiary types of the Rhynchota have been described, 

 most of these presenting no marked peculiarities as compared with 

 living types. The Palceontina oolitica of the Stonesfield Slate of 



