MAY FLIES AND MIDGES OF NEW YORK 75 



The foregoing description was made no doubt entirely from dry 

 examples. The words italicized and the stouter form of the in- 

 ferior appendages are almost the only characters which served 

 to separate the closely allied A. cognatella, a very critical 

 species regarding which I have some doubt. 



The superior (intermediate?) appendages of McLachlan, de- 

 scribed by liim as in the form of two contiguous yellowish bands 

 very strongly curved downward, appear to be separate at the base 

 only, the downturned tip being rounded. Between the divided 

 base escapes the penis, which is not shown in the figures here. 

 The construction of the socalled triangular pieces is very peculiar 

 and their appearance depends much on the degree to which they 

 are exserted. 



The North American insect is practically identical with the 

 European; the only difference appears to be in the upcurved con- 

 tiguous median processes which are probably rather shorter and 

 stouter in the American form. The latter was bred by Needham 

 at Lake Forest in June, and he sent the same species from Chic- 

 opee Mass. (23 April '03). It will probably prove to be common 

 in the Northern States. 



Orthotrichia americana Banks ? (Ent. News 1904, p. 116) 

 0. cristata Morton, U. S. 



The dorsal plate in the ^ is almost entire in its outer edge; 

 from the one side, on the upper surface, arises a short hook, while 

 on the other side, nearer the middle, arises a long, slender, much- 

 curved acute process bent strongly inwards under the plate itself. 

 The last ventral segment terminates in two separate blackish 

 plates which are broadest where they approach each other, nar- 

 rowing -outwards, their apices bearing a spine ; between these 

 plates is a black appendage which seen from the side is hook- 

 shaped and bears two spines. The seventh ventral segment with 

 a process covered with strong thick blunt hairs ; the sixth segment 

 with a small tooth. 



Lake Forest, 111. (Needham). 



The process on the seventh ventral segment is very similar to 

 that found in the European O. t e t e n s i i . 



