74 



No. 17 ('85, p. 264) which he thought might he fraternus is 

 probably not. Walsh states that he found this with other 

 species emerging in considerable numbers on the Mississippi 

 at Rock Island. Kellicott says that it is common in Ohio from 

 May to the first part of July, and flies about the swiftest and 

 most turbulent parts of the river ovipositing in rapids and 

 rough waters. The State Laboratory has a single imago taken 

 near the upper Sangamon, at White Heath, May 18. Fraternus 

 is chiefly eastern in its distribution; exiernus, western. In ad- 

 dition to the localities already given, the present species is listed 

 from New York, New Hampshire, and Virginia ; Michigan, In- 

 diana, and Arkansas.* 



9. GonijjJius extcrnus Selys. 



G. consobrinus Walsh. 



G. adelphics (suppos.) Hagen (nymph). 



The nymph of exiernus is readily recognized by the breadth, 

 form, and large lateral spines of the ninth segment, and by the 

 entire absence of dorsal elevations or hooks except a rudimen- 

 tary posterior tooth on the eighth and ninth segments. This 

 species and G. notatus are the most abundant gomphids in the 

 field of the Biological Station at Havana. They are usually 

 found in company, burrowing, mole-like, in the soft mud bot- 

 tom wherever a sufiicient current is maintained at all stages of 

 water, and becoming especially numerous in sheltered areas 

 where there is an accumulation of fine trash on the bottom. 

 They are quite common throughout the year in muddy flats 

 about the point where the waters of Quiver Creek become lost 

 in Quiver Lake, and along the line of the channels of the 

 Illinois and Spoon rivers, especially in the narrower part of the 

 Illinois down from the mouth of the Spoon. They are seldom 

 seen at any of the lake stations. Exiernus is also represented 

 in the State Laboratory collections from the vicinity of the 

 Mississippi River at Quincy, where it was common in the muddy 

 side passages and the adjoining narrow slough-lakes; from the 



*The images described as G. fraternus walshii _hy Kellicott (99) have been 

 determined by Calvert ('01) to be crassiis. See also foot-note on next page. 



