868. i 85 
, The neuration of the anterior wings is somewhat like that of the 
♦receding genus ; the vasa interna, however, are connected together by 
larger number of cross-veiulets. Forceps of (^ three-jointed ; their 
lasal joints much the longest. ? with the central seta rudimental, 
lot well developed, as in Polymitarcys. 
Genus Pentagenia, Walsh. 
Syn. Palingenia, Subgen. A. Walsh, 1862, 
Type P. vittigera, Walsh. 
The first ulnar rib is bipartite ; its bipartite anterior, and its bifid 
losterior, veins, both include a simple supplementary vein in their forks, 
nd the one in addition includes two or three supplementary veinlets. 
?he simple posterior ulnar rib is met not far from its origin by a simple 
upplementary vein, which is suddenly curved forwards towards the 
loint of contact (as in Ephemera), The very convex outermost veinlet 
rom the recurrent vein of the third vas internum, which is succeeded by 
ome very irregular, feeble veinlets, is distinctive of this genus. Forceps 
f ^ four-jointed, their second joints the longest. 
Genus Hexagenia, Walsh. 
Syn. Palingenia, p., Pictet ; Idem subgenus B., Walsh, 1862. 
Type S. limhata, Guer. 
Distrib. — Arctic America, Canada, United States, and the Amazons. 
The most obvious differences between the neuration of the anterior 
dngs of Hexagenia and Ephemera are the excess in number of the 
lore or less crowded, parallel, straight, veinlets extending from the 
bird vas internum perpendicularly to the internal margin, over those 
rhich unite it and the second supplementary rib. The recurrent 
ein of the third vas internum gives ofi" several nearly straight 
arallel veins. The ^ has the second joints of the four-jointed forceps 
be longest, and both sexes reject the central seta. 
Genus Epiiemeka, De Geer. 
Syn. Ejihemera, Lin., part. 
Type E. vulgata, Lin. 
Distrib. — Europe ; N. China, Hindostan, Ceylon (aberrant) ; 
ianada, Illinois. 
The forceps of Ephemera are similar to those of Hexagenia, but 
he central seta is sub-equal to the others. The cross-veinlets between 
