74 
No. 17 (85, p. 264) which he thought might be 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; externus, 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. Gomphus externus Selys. 
G. consobrinus Walsh. 
G. adelphus (suppos.) Hagen (nymph). 
The nymph of externus 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 sufficient 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. Hxternus 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 imagos described as G. fraternus walshit by Kellicott (’99) have been 
determined by Calvert (’o1) to be cvassus. See also foot-note on next page. 
