1868.] 



87 



Section B, L.fusca, Curt. 



Distrib. — England, Switzerland, Austria (Carniola), 2 sp. 



The posterior wing has the costa curiously excised in its apical 

 half ; and the basal joint of the forceps, instead of being upwards of 

 thrice as long as the other two together, equals them in length only. So 

 long as the subaqueous stages of development remain unknown, it seems 

 advisable to retain the species in the genus Leptophlehia. 



Genus Ephemeeella, Walsh. 



Syn. Fotamanthus, Pict., part. 

 Baetis, Walker, part. 



Type E. excrucians, Walsh = invaria, Walker. 



Distrib. — Hudson's Bay, Illinois, 2 sp. ; England, Spain, Switzer- 

 land, Grermany, 3 sp. 



The neuration differs from that of LeptopJilehia principally in the 

 following particulars. The foremost vas internum, instead of curving 

 forwards when it nears the base of the wing, and thus receding from 

 the second vas internum, runs straight up to the thickened root of the 

 wing alongside the second : it gives off a bipartite vein, and is itself 

 bifurcate. The second vas internum is simple, the third bipartite, and 

 united with the second by a cross-veinlet. The has 3-jointed forceps 

 (whose second joints are the longest), and ascalaphoid eyes (Mr. Walsh 

 ^ says those of invaria are simple). In its later subaqueous stages of 

 development the immature insect has six pairs of complex branchial 

 appendages, which are made up of a trapezoidal plate furnished under- 

 neath with a bipartite process, which supports several imbricated 

 lamellse arranged lengthwise. 



Genus Cloeox, Leach. 



Syn. C/oe, Burm., Pict., part. 



Chloeon, Lubbock. 



Cloeopsis, Etn., oHm. 

 Type C. dipterum, Lin. 



Distrib. — Lapland, Egypt, Madeira, France, Austria ; N. China ; 

 2 or perhaps 3 sp. A species (1 specimen in Brit. Mus.) is reputed 

 to be from S. Australia. 



Dipterous. During their later aquatic stages of development the 

 insects have six double pairs and a seventh single pair of branchial 

 plates. A series of short, solitary, supplementary veinlets is situated 



