604 



NEUROPTERA. 



in having tlifi anal angle of the posterior wings of the male 

 acute. u.'Eschna heros Fabr. is one of our largest and most 

 abundant dragon-flies. It is fuscous, marked with jellowish 

 green, and with two oblique green stripes on the side of the 

 thorax. 



In the third group of this immense farail}^ the Libellulina. 

 the wings are unequal, and the triangle of the anterior wings 



Fig. 588. 



is dissimilar, while the anterior genital hamule of the male is 

 free. In CorduUa the anal angle of the posterior wings of the 

 male is acute, and the body is brassy green. C. tenebrosa Say 



is found in the Western 

 States. 

 '*'■ Tlie genus LiheUuJa is 

 s, characterized by the short, 

 ' rather flattened abdomen, 

 narrowing rapidly towards 

 the tip, and the male clasp- 

 ino" organs are scarcely visi- 

 ble. Libelhda trimacnlata 

 DeGeer (Fig. 587, male) is 

 so called from the three 



Fig. 589. 



dark clouds on the wings of the female. The male difl'ers in 

 having a dark patch at the front edge of the wings, and a sin- 

 gle broad cloud just beyond the middle of the wing. Libel- 



