114 Annals Entomological Society of America [Vol. IV, 



nite 7 with its posterior portion overlapping sternite S and with its pos- 

 terior margin bilobed. Setae 3, nearly equal length, pilose; color 

 pale luteus with distinct brown rings at the joinings. 



Female subimago. Wings sub-hyaline and veins brown. Seg- 

 ment 7 not bilobed as in the imago. 



Nymph (PL VI, fig. 1; PI. VII, fig. 3; PI. VIII, fig. 5). Head and 

 body rounded and smooth, and without tubercles. Legs small in com- 

 parison with the size of the body. Head, rounded and without eleva- 

 tions (PI. VI, fig. 1). The left maxilla is shown on PL III, fig. 5. 

 Thorax, above smooth. Color, mottled brownish without definite 

 markings. Prothorax wider than the head its lateral margins slightly 

 flaring, and its width equal to that of the mesothorax; metathorax con- 

 cealed from above. Legs weak, the femora poorly developed and with 

 a row of hairs on its posterior margin (PL VII, fig. 3). Abdomen, above 

 rounded, gills present on segments 3-7, the posterior margins of segments 

 4-9 with a double median row of small spinose elevations; segments 3-9 

 with their posterior lateral angles produced into flat spines whose mar- 

 gins are spinose serrate. Setae brownish indefinitely banded with 

 whitish; basal joinings with circlets of hairs. 



Ephemerella cornuta, sp. nov. 



Occurrence, habitat. This, before mentioned species, was 

 reared at Salisbury, Connecticut. The dates given by Miss 

 Smith for its capture and rearing are July 20, 21. But two 

 stages, those of the male sub-imago and the nymph are repre- 

 sented. 



Measurements. 

 Length of body Length of setae. 



Male subimago 10.5 m. n. 



Nymph 10 m. m. 6. m. m. 



Male subimago, general color pale luteus with annular bands of 

 brown on the abdomen. Eyes prominent. Head with ocelli white, 

 encircled with broad bands of blackish brown; carina, frons and occiput 

 pale; antennae light brown. Thorax, above pale luteus; the prothorax 

 irregularly streaked with brown. Axillary cords of the fore-wing 

 produced into a slender point extending backward on either side the 

 median lobe of the metathorax, such prolongations not evident in the 

 hinder wing. Legs, pale, the fore femora lightly shaded with brown. 

 Wings, sub-hyaline, brownish at the base (PL IX, fig. 5). Abdomen 

 pale whitish, with annular bands of brown shading. Setae 3, whitish. 



Nymph. Body slender, and tapering from the mesothorax. Fore 

 femora shorter and wider than the others and with its anterior margin 

 unevenly toothed (PL VII, fig. 6). Head, with prominent incurving 

 horns just below the antennae; general shape sub-quadrangular with 

 the posterior angles rounded, and the frontal margin fringed with hairs 

 and projected forward; origin of the antennae partly hidden by the 

 curving ledges at the bases of the horns (PL VI, fig. 3). (Left maxilla 



