THE CANADIAN ENTOMOLOGIST 195 



usually with diffuse, dorsal longitudinal dark band, divided by a 

 pale median line, and sometimes with a definite row of dark spots 

 on the sides, legs pale, femora with a darker anteapical annulus, 

 which may be faint in pale specimens. Gills generally diffuse 

 greyish-brown, sometimes very pale, sometimes quite dark, typically 

 with three or four narrow, transverse, somewhat angular bars 

 about the middle or slightly beyond, following one another closely 

 and sometimes partly confluent, the first band usually the most 

 distinct and in very pale specimens sometimes the only one present. 

 In well-marked specimens there may be an indication of another 

 band farther distad, and in dark specimens there may also be 

 considerable pigmentation along the tracheal branches and some- 

 times dark blotches independent of the tracheae. 



Length of body 21-21.5 mm.; hind wing-pad 4-4.8 mm.; 

 hind femora 3.8-4.4 mm.; gills 7.5-8.5 mm. 



As in the case of the adults, the nymphs of E. cyathigerum 

 and calverti differ apparently only in one constant character, the 

 form of the superior (lateral) abdominal appendages of the male. 

 In the nymph of calverti these appendages in profile appear fully 

 as deep as long, with a much broader and more bluntly rounded 

 apex, which is somewhat above the mid-longitudinal axis. The 

 sulcation seen in cyathigerum in an oblique \'iew from above is 

 not present in calverti. The outline of the appendage viewed 

 directly from above is less rounded than in cyathigerum, the outer 

 margins being but slightly curved, and passing into the posterior 

 margins by a rounded angle. There is a distinct submedian longi- 

 tudinal ridge. 



Ris' figure of the gill of a European specimen of E. cyathigerum, 

 reproduced from a photograph, differs considerably from the gills 

 of my specimens, being more like those of E. hageni and E. ebrium- 

 in form. It is little more than three times as long as broad; the 

 margins are more evenly convex, and the marginal spinules appear 

 decidedly smaller, those of the stronger series not interrupting the 

 curve of the margin as in American specimens and in E. calverti. 

 In Ris' figure, the gill is broadest beyond the apex of the spinulose 

 part of the margins, while in American specimens the greatest 

 width is just before this point. The gill is also described as having 

 no transverse bands and none appear on the figure. 



