March, 1921] Macro-Fauna of Mirror Lake 157 



eral existence, or of the cast nymphal skins. Specific deter- 

 mination unfortunately was not possible. Very young spec- 

 imens were not included in the genus identification and hence 

 not counted in the table. 



Hexagenia sp. Two specimens of a large species of burrow- 

 ing nymph, were uncovered at the time of the draining of the 

 lake, June, 1920. They would not have been recorded other- 

 wise. They were partly in the mud, some distance from shore, 

 near the west end of the large pond, nearest station 9. It was 

 probably scarce in Mirror Lake. 



Heptagenia sp. A few specimens of this were found clinging 

 on the under surface of a large, submerged stone (station 7). 

 Since this sort of habitat could easily be investigated and no 

 more were disclosed, it must be deemed rare. 



Caenis sp. This form was found at various points ojff shore 

 on the bottom mud and silt, chiefly in the large pond. Though 

 only a small number were secured probably it was not uncom- 

 mon. The large pond may have harbored many, so as to have 

 made it more common than Callibcetis. 



Callibaetis sp. This form, (Needham '18), "an active 

 climber among green vegetation," was found almost exclusively 

 in the small pond, at a number of stations. It was common. 

 An odd occurrence was a relatively large number in the shallow 

 open water of station 17. 



Order Odonata. 



Adult dragon flies and damsel flies were common about 

 the pond most of the season. Damsel flies especially were seen 

 hovering over grasses on the margin. There many were collected 

 several times during the summer. Dragon flies were not taken; 

 those commonly present were recognized. A few strong fliers, seen 

 only occasionally, are not listed, as very likely their early life 

 history was not lived in the pond. Of the entire order, only 

 such species of which nymphs were obtained from Mirror Lake 

 are listed, except one or two, which unquestionably must have 

 passed their early life history there. It is likely that not as 

 comprehensive a collection of dragon fly nymphs was secured, 

 because of their generally obscure haunts, as of the damsel 

 fly nymphs. 



