NATURAL SCIENCES OP PHILADELPHIA. 377 



The 9 subimago is of a nearly uniform obscure fuscous color, the abdomen 

 with only a trace of the pale colors of the imago. The legs are obscure green- 

 ish, immaculate, the front legs a little the darkest. The three setae are equal, 

 greenish-fuscous and pilose ; and the wings slightly tinged with fuscous and 

 ciliate behind. 



Length 9 1011 mill. Alar expanse 9 2426 mill. Seta? (3) 9 10 mill. 

 Two 9 i c? unknown. This is probably E. simulans "Walk. Cat. I obtained 

 all my specimens in company on the Desplaines River, near Chicago. The 

 imago differs from Dr. Hagen's diagnosis by the thorax not being " luteous " 

 above and the wings not " yellowish-hyaline." 



Ephemera flaveola, n. s. ^ Yellowish. Vertex ferruginous ; orbits of 

 ocelli and basal joints of antenna? a little dusky ; seta pale. Thorax pale 

 ferruginous. Abdomen with a lateral pale fuscous vitta on joints 3 7 inter- 

 rupted at the sutures ; setae not quite of equal length, whitish, with the 

 incisures regularly fuscous. Legs yellowish, the anteriors with the terminal 

 half of the femora ferruginous, and the tips of the tibia?, the first tarsal joint, 

 the incisures of the others and the tarsal tips, fuscous ; the hind legs with 

 only the tarsal tips fuscous. Wings hyaline, with a slight yellowish tint on 

 the costa, the veins and cross-veins fine, subequal, hyaline, except the 

 three costal veins and the basal cross-vein which are coarse and yellowish. 



The 9 differs only from the $ in the abdomen being egg-yellow wherever 

 it contains eggs ; and in the cross-veins of both wings being fuscous, except 

 at the tip and along the posterior margin. 



Length tf 7- 91 mill. $ 9 10} mill. Alar exp. J 1 1719 mill. 9 19 

 20 mill. Seta? tf 20 mill. 9 12 mill. Interm. seta tf 14 mill. 9 10 mill. 

 Ant. leg $ 8^ mill. 9 (same size) 6 mill. Four tf, three 9 



The cf 1 9 subimago differ from $ 9 imago only in the seta? being subequal, 

 obscure pale greenish and pilose, and in the wings being subopaque, tinged 

 with dusky, and ciliated behind ; in one $, but not in 9 > the veins and 

 cross-veins are slightly dusky. 



Length rf 7 9" mill. 9 81 mill. Alar exp. $ 1920 mill. 9 20 mill. 

 Seta? (3) tf 912 mill. 9 12 mill. Two <?, one 9 . 



Ephemerella, new genus (= Leptophlebia, Westw. ?) 



Three long and equal caudal seta? ; wings four, hind wings wide with several 

 veins ; transverse veins rather numerous, absent, except the basal cross-vein, 

 on the basal two-thirds of the costa of front wing, and the hind margin of both 

 wings, where there are many short, isolated veinlets ; eyes $ simple, con- 

 tiguous ; ocelli three, nearly transverse, contiguous <j\ somewhat remote 9 

 First tarsal joint indistinct, except in anterior $ tarsus ; more than one-half 

 as long as joint 2, except in anterior $ tarsus where it is less than one-fourth 

 as long ; joints 2 4 subequal in all the $ 9 legs, 4 rather the shortest. 



Ephemerella excrucians, n. sp. <^ Yellowish. Eyes in tbe living insect 

 egg-yellow on their upper three-fourths, pale fuscous on their lower one- 

 fourth ; vertex and antenna? ferruginous ; seta and orbits of ocelli fuscous. 

 Dorsum of thorax and of abdomen ferruginous, the latter sometimes almost 

 piceous ; seta? whitish, with regular fuscous incisures, becoming indistinct at 

 tip. Legs all pale yellow, with the tips of all the tarsi and in the anterior 

 legs the first tarsal joint and the tarsal incisures, cloudy. Wings hyaline, with 

 a slight yellowish tinge on the costa ; veins moderate, cross-veins fine except 

 on the costal tip, all hyaline. 



The 9 differs from the $ in the veins on the anterior part of the wing 

 being slightly tinged with fuscous. 



Length $ 51 71 mill. ; 9 5161- mill. Exp. J> 14118 mill. ; 9 15 

 19 mill. Seta? tf 1113 mill. 9 10 12^ mill. Ant. leg c? 7 mill. 9 (same 

 size) 41 mill. Twelve <j\ five 9 



1862.] 



