PSEUDONEUROPTERA. 75 



ures only 6 mm., and the tarsi are very long. These two species are our most 

 common representatives of this division of the Gomphinae. 



CORDULEGASTERIN^E. Our only genus is C or duleg aster, of which but few 

 species are found in the United States. 



CORDULIN^E. We have three genera of this sub-family, each of which is 

 well represented in our fauna. These are Macormta, Epttheca, and Cord&lia. 



LiBELLULlN^E. This sub-family is represented in our fauna by at least ten 

 genera. 



Family III. PERLIM;.* 



Order PLECO'PTERA of some authors.f 



(Stone-flies^) 



The family Perlidce includes comparatively few species ; but 

 members of it are common about any of our creeks. These insects 

 are called Stone-flies because the immature forms are very abun- 

 dant under stones in the bed of streams. The adults are found fly- 

 ing about or resting upon herbage in the vicinity of water. 



The body is depressed, elongated, and with the sides nearly par- 



FIG. 72. Pteronarcys regalis. 



allel (Fig. 72). The prothorax is large. The antennae are long, 

 tapering, and many-jointed. The wings are unequal, the second 

 pair being the larger, and lie upon the abdomen when at rest. The 

 tarsi are three-jointed ; and in most species the caudal end of the 

 abdomen is furnished with two setae. 



* Pedidze, P6rla: a proper name. 



f PlecSptera: pieces (itXeKoS), plaited; pteron (Ttrepov\ a wing. 



