276 THE CANADIAN ENTOMOLOGIST. 



A single male specimen, collected end of June, 1898, five miles 

 north-east of Flora, 111., Little Wabash River, by J. F. Garber, in 

 the collection of Mr. Chas A. Hart, who has very kindly offered me the 

 specimen for description. It belongs to the subgenus Arigomphus, and 

 G. pallidum is perhaps its nearest ally. 



Gomphus cavi/laris, n. sp. 



Length 41 mm., abdomen 30 mm., hind wing 24 mm. 



Face yellow, tinged with brown on the sutures and on the middle of 

 the labrum. Vertex blackish, except the postocellar ridge and a narrow 

 basal ring around each antenna. Occiput yellow, straight, or very 

 slightly convex at its ends, with a thin fringe of black hairs. 



Prothorax brown, with median and lateral spots of greenish yellow. 

 Dorsum of the thorax greenish yellow, with a triangular median stripe of 

 brown, divided on the carina, greatly dilated below, almost interrupted on 

 the collar. Humeral and antehumeral stripes distinct, the latter isolated 

 above. Sides greenish yellow, with narrow pale brown stripes on sutures. 

 Legs entirely reddish beyond the trochanters, with black spines and black- 

 tipped claws. Wings hyaline, costa yellow, stigma fulvous. Antecubitals 

 of fore wing 9, of hind wing 7, postcubitals 6-7 on all wings; the istand 

 4th antecubitals of the hind wings hypertrophied. 



Abdomen brown, with ill-defined middorsal stripe of yellowish green, 

 disappearing on segments 8 and 9. Sides of segments 1 and 2, including 

 the auricles and base of 3, greenish yellow ; indistinct lateral paler marks 

 also on 4-6 ; sides of 7-9 bright yellow inferiorly, superiorly fulvous; 10 

 brown, paler below ; appendages brown. Apex of segment 8 cut very 

 obliquely, longer on the dorsal side. 



Appendages brown, the superiors scarcely longer than the inferiors, 

 and scarcely more divergent, obliquely truncate, with the inner angle 

 produced into a long, straight, posteriorly-directed point, the external 

 angle also acute, short, situated at two-thirds their length. Viewed from 

 the side, the external angle presents an inferior tooth, and beyond it on 

 the outer margin are two other smaller teeth before the apex, one near the 



