83 
Length 23 mm. Body flat ; lateral labial lobes with a sharp 
bent apical hook, and but three strong teeth near tip; abdo- 
men tapering slowly from 7th segment, 9 one third longer than 
8, 10 very short, one sixth of 9; lateral spines on 6 to 9, sharp, 
the last pair twice the length of 10; no dorsal hooks, except 
that 9 bears a broad, triangular, flat, median apical projection 
as long as 10; appendages twice as long as 10. 
18. Gomphus amnicola Walsh. 
? G. olivaceus (suppos.), Hagen, '85, p. 271, No. 27 (nymph). 
This and the remaining species here treated belong to the 
subgenus Sty/urus. Williamson has made a thorough study of 
this troublesome group of species. A copy of his revision of 
the subgenus (Williamson “O1b) has been received from him 
just as these pages are being set up by the printer, enabling us 
to incorporate his data concerning the geographical and sea- 
sonal distribution of the species, derived from a large number of 
specimens examined by him. 
A single nymph in the State Laboratory collection, taken 
at Colona, Henry Co., Ill, August 20, is almost identical with 
that described by Hagen from Utah and connected by supposi- 
tion with G. olivaceus. It stands in about the same relation to 
Gomphus notatus that the imago amnicola does, and may be 
assigned to this species. 
Mr. Needham is of the opinion that the affinities of both 
the present species and G. scudderi are with the di/atatus, rather 
than the plagiatus (Stylurus Needh.), group of species, in which 
case the nymph here assigned to amnicola may be wrongly 
placed. It is earnestly to be hoped that the nymphs of these 
species may soon be discovered, as this would doubtless throw 
much needed hght on their specific relationships. 
The imago of this species has been taken in Illinois only 
along the Mississippi in the northwestern part of the state, and 
by Mr. Longley at Riverside, near Chicago. It was found at 
Rock Island and described as new by Walsh. Our specimens 
were captured at Savanna, August 1, by Mr. F. M. McElfresh. 
