272 Kev. A. E. Eaton on 



many instances solitary specimens, more or less defective, 

 that have been relaxed and spread out, and by being thus 

 treated have suffered loss of, or detriment to, their body- 

 markings. Where it was not justifiable in such circumstances 

 to name an insect as a species, it has been deemed desirable 

 to name as nearly as possible the genus to which it should be 

 referred, noting, by illustration or description, characteristics 

 likely to aid in the recognition of other specimens of the 

 same species o£ flies from at least the identical localities. 

 Some wings, detached, have been mounted in Canada balsam, 

 to enable them to be examined and figured as to neuration. 

 Hind wings of dried May-flies are apt to be shrivelled up ; 

 if detached and let fall upon hot water they can usually be 

 induced to unfold (with the exception of the marginal area) 

 on the surface of the water. Taken up from that on thin 

 glass or a feather, while thus expanded, they can, while 

 moist, be floated off from it on to distilled water and cleaned 

 without being submerged. Then, transferred in a similar 

 manner to a prepared cover-glass for the object to be mounted 

 for the microscope (already in position on the centring-card, 

 and with bits of distance-glass in position, as well as the space 

 for the object duly moistened), the wing can be adjusted upon 

 the glass, and the ordinary method of preparation be com- 

 pleted. No attempt to submerge the wing afloat should be 

 made prior to its being hardened in spirits. 



Elassoneukia, Etn. (1881). 

 Kelated to Oligoneuria, Pictet (1843-5). 



Elassoneuria Candida, sp. n. 



? Subimago $ (dried). — Wings dull, light, transparent 

 smoky grey, with the stronger veins and cross-veins opaque, 

 light sepia-grey. Cross-veins in the marginal area simple 

 and indefinite (this area folded over) ; below the vein E- 1 13, 

 within the sectorial fork 7, and 13 very faint and whitish 

 below this fork and its stem. Epinotal prolongations of the 

 wing-membranes, reaching to the base of the third dorsal 

 segment, blackish. Dorso-lateral points of the ninth abdo- 

 minal segment extend rather beyond the insertions of the 

 caudal setae. Last ventral plate, on each side of its terminal 

 sinus, produced into a subacute point. Markings of the 

 thorax and abdomen similar in character to those of the 

 imago. 



