122 



first anal cell on its outer side (M) is longer than that portion of the anal vein 

 bounding the outer side of the same cell (S). In Gomphus M is always shorter 

 than S, unless a vein between post-anal cells meets S, as in fig. 4. The Gompbi 

 occurring in Indiana can be readily separated into three groups on characters of 

 the post-anal cells. 



I. Second branch of anal vein not angled where the first cross vein be- 



tween post-anal cells meets it (at point T) ; normally two post- 

 anal cells in the first series (fig. 4). (North American and 

 European.) 



II. Second branch of anal vein angled at point T; normally one post- 



anal cell in first series, two in second (fig. 5). (North American.) 

 III. Second branch of anal vein angled at point T; normally one post- 

 anal cell in first two series, followed by two (fig. 6). (North 

 American. ) 

 Lanthus is similar to this Group III of the genus Gomphus. It may be 

 separated by the character indicated above. 



The species of Gomphi known to occur or possibly occurring in Indiana may 

 be arranged in these three groups, as follows: 



I. brevis. II. (?) pallidas. III. externus. 



viridifrons. villosipes. fraternus. 



quadricolor. (?) cornutus. crassus. 



exilis. ventricosus. 



sordidus. vastus, 



spicatus. dilatatus. 



graslinellus. amnicola. 



furcifer. plagiatus. 



(?) pallidus. notatus. 



spiniceps. 

 Prof. Hine and Mr. Tough have studied G. cornutus and G. pallidus for me. 

 From their sketches I believe both species will come in Group II, but the ma- 

 terial is so scanty I can not be sure of this. 



11. Gomphus viridifrons Hine. PI. I, figs. 16 and 17. Described in the 

 Ohio Naturalist, Vol."^, No. 4^p. 60, Feb., 1901. The color description is quoted 

 below . 



"Length of the abdomen, about 33 mm..; hind wing about 27 mm.; black, 

 face and occiput green; prothorax with anterior margin and three spots, green 

 or yellow ; thorax green with spaces at base of wings, lateral suture and six bands 

 before, black; the two middle binds are abbreviated anteriorly and separated by 



