52 The Ottawa Naturalist. [June 



This large genus may be known from the alhed genera 

 mentioned by the following group of characters: Triangles 

 without cross-veins, thorax green or yellow with conspicuous 

 brown or black bands, hind femora with numerous small spines, 

 but no large ones. 



19. GoMPHUS vastus (Walsh). Fig. 3. 

 Hull, June 29th, 1886, 3 females (Fletcher). 



Face transversely banded with black, dorsum of thorax 

 with a pair of narrow equal divergent yellow bands, each forming 

 below an acute angle with a shorter transverse band and uniting 

 above w4th a narrow complete antehumeral band. Segments 

 7-9 remarkably dilated, especially in the male. 



This species is said to frequent the shores of the Great 

 Lakes and larger streams. I have never met with it in the field. 



One of the above specimens was recorded under the name 

 G. adelphtis in the Entomological Record, Ann. Rep. Ent. Soc. 

 of Ont., 1906, p. 104. 



20. GoMPHUs p>REvis (Hagen). Figs. 4, 5. 



Ottawa, 1 male; Hull, June 29th, 1886, 1 female (Fletcher); 

 Cumberland, June 16th, 1900, 1 male (Gibson). 



Face transversely banded with black, dorsum of thorax, 

 with a pair of broad green or greenish yellow bands widening 

 below. Antehumeral bands interrupted above. Segments 7-9 

 only moderately dilated. 



This short, thick-set species is rather common in Ontario, 

 frequenting well aerated waters, such as rapid streams and the 

 exposed shores of large lakes. 



21. GoMPHus ExiLis, Selys. Figs. 6, 7. 



Ottawa, 1 male,. 1 female (Harrington); Hull, July 13th 

 and 17th, 1907, 3 males, 1 female (Gibson). 



Face entirely yellow, length under 45 mm., dull brown 

 banded with greenish yellow, segments 7-9 but little dilated, 

 superior appendages of male with a blunt low inferior process. 



This is our commonest Gomphus, frequenting the shores 

 of lakes and streams, especially the more sheltered parts. It is 

 exceedingly abundant on Georgian Bay. 



G. spicatus and G. sordidus are often associated with G. exilis, 

 and both closely resemble the latter in form and coloration. 

 They are larger species (48-50 mm.) and differ from exilis 

 further in the structure of the genitalia. 



22. GoMPHUs coRNUTus, Tough. Figs. 8, 9. 

 Ottawa, Mer Bleue, June 18th, 1907, 1 male (Fletcher). 

 Face entirely yellow: length (male) 5" mm.; dorsum of 



