62 DRAGONFLIES OF OHIO. 



"the space between the lateral thoracic lines livid," 

 but of the more usual greenish yellow hue ; the verti- 

 cal thorns are black and conical ; the posterior femora 

 are either with or without external vittae, in this re- 

 gard agreeing with the female of fraternus. t has 

 been said that the latter has no vertical thorns, and 

 that the females of externus and fraternus may thus 

 be separated ; this will not do, for the female fraternus 

 has long ' slender, black or yellow vertical thorns ; 

 they are easily separated, however, by the difference 

 in the occiput — fraternus with a spine in the middle 

 of the border, externus having the same straight or 

 slightly concave — externus is larger and the vitta 9 is 

 almost as conspicuous as in externus. 



Easily separated from fraternus by the wide yellow 

 vitta on the ninth abdominal segment, its larger size 

 and straight or concave occiput. 



Common along the Olentangy river at Delaware 

 and Columbus in June. 



Gomphus graslinellus, Walsh. 



Length of abdomen cT and 9 39, of hind wing c? 

 33, 9 34. 



Male black, yellow and greenish yellow. Head; 

 occiput yellow, slightly convex, fringed with short, 

 black hairs, rear yellow with the upper parts of the 

 orbits brownish or black, vertex and antennae black. 

 Prothorax black with a bright yellow spot on the 

 anterior border, base with a spot each side and one 

 between them yellowish ; thoracic carina brown with 

 a similar colored space each side, humeral and ante- 

 humeral bands present, separated for their whole 

 length by a narrow yellow stripe, first and second 

 lateral sutures margined with brown ; wings with the 

 costse greenish yellow ; legs, femora and tarsi black, 

 tibiae black with a yellow dorsal band as follows : a 

 rather wide, uniform band on 1 and 2, a narrower, 



