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. GompliKS amnicola Walsh. « 



? G. olivaceus (suppos.), Hagen, '85, p. 271, No. 27 (nymph). 



This and the remaining species here treated belong to the 

 subgenus Sfi/hir/ts. Williamson has made a thorough study of 

 this troublesome group of species. A copy of his revision of 

 the subgenus (Williamson '01b) 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., 111., 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 (ntuiico/(f does, and may be 

 assigned to this species. 



Mr. Needham is of the opinion that the aftinities of both 

 the present species and G. scudderl are with the d'datatus, rather 

 than t\\Q plagiatKS {Styhinis Needh.), group of species, in which 

 case the nymph here assigned to anniirohi 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 light 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. 



