90 [September, 
The neuration of the fore-wings, and the proportions of the forci- 
pa] joints, are very similar to those of the last genus. But the eyes of 
the (^ are simple, and the central seta is rejected. The sides of the 
dorsal arcus of the last well-formed segment of the abdomen are pro- 
longed posteriorly so as to form an acute, more or less flattened, spine 
on each side in all of the genera from Bcetisca to the present genus 
inclusive. 
Genus Heptagenia, Walsh. 
Syn. Baetis, auct. part. 
Ecdyurus (misspelt JEcdyonurus) Etn. 
Distrib. — N. Hemisphere ; and, according to M. Blanchard, Chili. 
Ihe principal difference between this genus and the preceding, in 
the neuration of the wings, is that the first of the supplementary ribs 
between the vas ulnare and vasa interna terminates at some distance 
in advance of the angle of the wing, and supplies with veinlets no part 
of the internal margin ; that portion of the inner margin which is 
included by the two supplementary ribs receiving upwards of four 
supplementary veins and their veinlets. The first joint of the 3-jointed 
forceps is the longest. Egg-valve entire. Central seta rejected. Eyes 
entire in the male. 
Type H.flavescens, Walsh. 
Distrib. — England, 4 sp. ; Germany, &c., N. America. 
Lobes of the penis divergent. Wings of the sub-imago with the 
cross-veinlets not margined with a darker colour than that of the rest 
of the wing, and of the same colour as the wing until shortly before the 
last moult. 
Section B, II . venosa, Eab. 
Syn. Ecdyurus, Etn. 
Distrib.— England, 3 sp. ; Europe, &e. 
Lobes of the penis slightly separated, horizontally flattened and 
triangular. Cross-veinlets in the wings of the sub-imago conspicuously 
margined with a darker colour, in most species. At the time when I 
proposed the name Ecdyurus for this genus, I imagined that Mr. Walsh's 
Heptagenia was a dismemberment of Palingenia, Burm. ; but he having 
kindly forwarded to me, for the British Museum, types of his new genera, 
I find that Heptagenia is the same as Baetis, Burm., Pict. 
Having now surveyed the genera, I will attempt to point out the 
affinities presented by them one to another. The family seems to con- 
