MAY FLIES AND MIDGES OP NEW YORK 45 



This species differs in the nymphal stage from the nymph next 

 described, chiefly the presence of well-developed dorsal hooks and 

 the absence of black rings on the base of the setae. 



Ephemerella unicornis sp, nov. 



Along with the six specimens of E . b i s p i n a came a single 

 male of another apparently very distinct species, distinguished 

 at a glance from all the others by an erect conic tubercle upon the 

 front margin of the middle lobe of the mesothorax. This species 

 is notably smaller, measuring but 5 mm. in length, with the setae 

 of the same length and the wing hardly longer. The hind wing 

 also is marked with a more distinct basal costal angulation than 

 is common in this genus. The spines beside the backward pro- 

 longation of the middle lobe of the mesothorax are present also 

 in this species but apparently not so large. Unfortunately the 

 specimen, although perfect, is a subimago, and the mature colora- 

 tion can not be given; it will probably be brownish since in the 

 subimago it is greenish as in E . b i s p i n a . The abdominal 

 appendages are well enough developed to show that the end seg- 

 ment of the forceps will be much shorter than inE. bispina, 

 while the inner appendages will probably be of the same type as 

 in that species, though probably relatively shorter. 



Ephemerella sp?, near ignita 



This species occurs at Ithaca, but I have thence but a single 

 njTnph. There are two nymphs in the U. S. National Museum 

 labeled " From stream on Mr Chamberlain's farm, Richfield 

 Springs, N. Y., May 13, 1837." It is very closely allied to the 

 European E . i g n i t a , as figured and described by Eaton 

 (Monograph, pl.40 ; whole figure copied in Cambridge Natural 

 History, vol.5, p.436, fig.282). 



One of the two nymphs from Richfield Springs is apparently 

 grown. It measures in length 8 mm., setae, 3.5 mm. additional. 

 Body rather more elongate than in the typical species; eyes lat- 

 erally prominent; abdomen (pl.lO, fig.7) strongly depressed, the 

 usual submedian double row of dorsal tubercles scarcely indicated. 

 Lateral spines, thin, flat, sharp, on segments 4-9, a mere tooth on 

 4, increasing in size thereafter to segment 8, broader and less 

 sharp on 9. Gills present on segments 4-7, double, on 4 scarcely 



