262 SYSTEMATIC ARRANGEMENT. 



important character of having a sucking instrument 

 with a jointed sheath, and it must he admitted to he 

 highly inadvisable to multiply orders except for the 

 most urgent reasons. But if rejected as primary 

 groups, they must he adopted as secondary ones ; and 

 we shall accordingly follow Latreille, who has, from 

 this circumstance, divided this order into two great 

 sections, which he denominates Heteroptera (wings 

 of different texture) and Homoptera, (wings of uni- 

 form texture.) 



The under wings are usually not of large size, and 

 offer nothing peculiar in their forms and composition. 

 When at rest they are covered hy the hemelytra, 

 being simply drawn beneath them, and more or less 

 crossed, but without forming distinct longitudinal or 

 transverse folds. Several species of Hemiptera are 

 entirely apterous. 



This is the only order in which upper wings of a 

 rigid consistency coexist along with a mouth formed 

 for sucking. The latter differs considerably from the 

 spiral tube of butterflies and moths, which is a mere 

 canal for conveying the nutritive fluids into the eso- 

 phagus ; besides serving this purpose, it is so formed 

 that it acts as a lancet for piercing the integuments 

 of plants and animals. As great length would scarcely 

 be compatible with such a usage, it seldom equals the 

 dimensions of a lepidopterous proboscis, being usually 

 much shorter than the body. There are a few ex- 

 ceptions to this rule, however, and in some examples 

 it is so long as to project a good way behind the body 

 like a caudal filament. Although so different in ap- 



