July, 1831.] 25 



Nymph with seven lateral pairs of abdominal tracheal branchiae ; 

 the laminae small, nearly alike in form, reflected backwards and out- 

 wards, with their edges up and down ; their tracheae indistinct ; the 

 fibrils abundant, and about as long as the lamina. Head rounded and 

 broadly flattened out ; postero-lateral angles of pronotum rectangular 

 or obtuse ; labrum not obvious, a velvety fold of the palate taking its 

 place. Mandibles terminated by two strong slender fangs, of which 

 the outermost is the stronger, and is about as long as the interval 

 between the base of the other and the point of the molar v tuberosity. 

 First joint of the upper maxillary palpus about two-thirds as long as 

 the second, and rather stouter than it. Lateral lobes of the tongue 

 broader than the median lobe. Caudal setae three. Type, H.flaves- 

 cens, Walsh. Distrib., Europe, N. America, Cape Colony. 



Ecdyurus, Etn. (revived ; misspelt Ecdyonurus in Trans. Ent. Soc. 



Lond., 1868, p. 142, n. ; corrected in E. M. M., v, 90). 



Imago. Hind tibia of £ about once and three-quarters as long as 

 the tarsus, whose proximal joint is almost one-ninth as long as the 

 tibia. Fore-tarsus in <$ nearly, or quite, twice as long as the tibia, 

 rarely so little as one and two-thirds as long ; in $ from three-quarters 

 as long, to almost the same length, as the tibia ; the proximal joint in 

 <$ from nearly one-third to four-ninths, in $ from about one-fifth to 

 one-seventh as long as the tibia. Relative lengths of the tarsal joints : 

 —fore-foot, J, 12, 21, 227, 17, and 9, or 23, 31, 33-5, 23, and 175, or 

 19, 30, 28 7, 22, and 18 ; in ? , 7, 8. 7, 4, 7, or 7, 9, 8, 5, and 8 ; hinder 

 feet, £ , 5, 4, 3'5, 2*5, and 6. Caudal setae in £ two and a half to 

 three times as long as the body, in $ about once and a half as long. 

 Penis lobes very broad. 



Wings of the sub-imago at first greyish with dark neuration, 

 usually edged with grey ; afterwards, in most cases, dark transverse 

 bands and fasciae appear in the disc of the fore-wings. 



Nymph with seven lateral pairs of tracheal gills, the first the 

 smallest ; laminae reflected obliquely outwards : with distinct tracheae ; 

 the branchlets of the median trachea usually p innately arranged in some 

 of the laminae ; fibrils nearly as long as the lamina in the first three 

 pairs, and nearly half as long as it in the others. Head rounded and 

 broadly flattened out ; postero — lateral angles of the pronotum prolonged 

 backwards. Labrum distinct, small. Mandibles with two strong 

 slender fangs, the outermost of which is about one-third as long as the 

 interval between the base of the other and the point of the molar 

 tuberosity. First joint of the upper maxillary palpus about half as 



