on the Ephemeride. 85 
Belust. ZL. stigma & talcosa, Ste. 1835-6; Potamanthus 
stigma & talcosus, Pict. 1843-5. P. marginatus, Hag. 1863. 
Subimago, v. v.s. Ala fuliginosz vel corvine, venis 
flavescentibus, transversalibus anguste nigricante mar- 
ginatis; postice bases versus vel in toto pallidiores, 
nervis transversalibus apud margines terminales nigri- 
cantibus. 
Imago, v.v.s. 4. Oculi piceo-hepaticolores, vel rufo- 
fuliginosi. Tergum thoracis fuscum vel aterrimum, 
politum. Ale vitrine, nervis fuscis: antica apicibus 
aree marginalis et arez submarginalis fuscis vel sub- 
fuliginosis. Pedum antici nigro-picei, tarsis cinereis: 
posteriores picei vel fusco-lutei, tibiis interdum brunneis, 
tarsisque plus minusve fuliginosis. Abdomen ferme 
supra fuscum vel fusco-piceum, juncturis flavescentibus, 
infra fuliginosum, juncturis pallidis, et maculis satura- 
tioribus sub plexus nervorum: interdum tamen seg- 
mentorum 2-7 cinerea sunt, lineis spiracularibus satu- 
ratis, maculisque sub plexus nervorum luteis, atque 
cetera sunt fusco-picea. Sete atra, vel cinereex, junc- 
turis vix obscuratis. Forceps fuliginosus vel testaceus. 
@ vel mari similis ; vel abdomine supra piceo, apici- 
bus segmentorum saturatioribus, et subtus atr o-fuliginoso, 
tibiis anticis testaceis. Processus ventralis penultimi 
segmentorum incisus est. 
iiongr. corp: 6-12, 9 6-11; al. @«7-11,9. 7-12; 
set. ¢ im. 12-20, subim. 9; set. 9 im. 8-16 mm. 
Hab.—Temperate and Arctic Europe and America. 
In England it appears in April, May, July, September 
and October, and frequents rivers. 
Leptophlebia helvipes. 
(Genitalia maris, Pl. IV. fig. 26, 26 a-c. Ala postica, 
fig 26d.) 
Ephemera helvipes, dispar & submarginata, Ste. 1835-6. 
Potamanthus Geerii, helvipes, dispar, & submarginatus, 
Pict. 1843-5. Baetis reticulata, ? Burm. 1839. Cloeon 
euliciformis, Walk. 1853. 
Subimago, v. v. s. Ale cervine vel nigricantes, 
nervis transversalibus late nigro-marginatis ; paucitas 
horum in medio ale anticz maculam transversalem circa 
coste medium pellucidam facit. 
