84 
Single examples are also listed from Galena, II]., and from Iowa 
(July), Kansas, and New York. It was taken by Mr. Longley 
in June. 
The principal characteristics of the nymph are as follows: 
Nymph (supposition) very similar to G. notatus ; median 
labial lobe rounded but short, lateral lobes similar to those of 
notatus ; abdomen broader, more lance-shaped ; 9 a little longer 
than 8, with a very short apical spine above ; lateral spines on 
6 to 9, the last one blunt, half as long as 10, which is short, ey- 
lindrical ; appendages and legs similar to to those of notatus. 
19. Gomphus plagiatus Selys. 
GC. fluvialis, Walsh (female). 
G. notatus, Hagen, ’85, p. 270, No. 25 (nymph). 
G. plagiatus, Hagen, '85, p. 269, No. 24 (nymph). 
This is probably the most abundant gomphid nymph in the 
larger rivers of Illinois. It may be distinguished from any 
others herein described by the penultimate (ninth) abdominal 
segment, with its lateral and basal margins about equal and a 
rudimentary posterior tooth on the median dorsal line, the 
other segments being without trace of dorsal hooks or eleva- 
tions. As already stated under externus, it is found about 
Havana in muddy bottoms where there is current, but not so 
exclusively in these situations as erternus. Mr. Garman re- 
ported it as the commonest species in waters associated with 
the Mississippi at Quincy, and states that it does not breed ex- 
clusively in running water, presumably basing this statement 
on the fact that he found it in slough-lakes. These lakes form 
channels of flow during higher stages of the river, but are more 
or less completely isolated during low water. Unlike similar 
waters about Havana, these lakes are but scantily supplied 
with aquatic vegetation. In our general collection are nymphs 
from Cairo, Ill., where they are probably common, judging from 
the number taken ; from the Rock River at Colona and Milan ; 
from the Ohio at Golconda; and from the Illinois at Pekin. 
The species did not appear in extensive collections from the 
Sangamon in Champaign county. The nymphs were not more 
