During the month of August, 1935, Mr. W. J. Brown, who accompanied the Arctic trip of the S. S. Nascopie, was enabled to make insect collections at Lake Harbor, on the south coast of Baffin Island.

The only species of Ephemeroptera obtained were two Baetids which were plentiful in both nymphal and adult state and for which definite associations between nymph and adult were secured.

The one species, which occurred in both sexes, bears so much resemblance to Acentrella lapponica Bngtsson. that I am holding it under this name pending an examination of some of the material by Professor Bengtsson. The second species, a typical Baetis, could only be found in the female sex, nor could Mr. Brown, in spite of diligent searching, discover any imales amlongst the mature nymphs in the brook; it would seem that the species was parthenogenetic, at 1east as far as thecycle emerging in August was concerned. On nymphal characters it falls in the bicaudatus group, with the middle tail reduced to a stub, but can at once be separated by the much larger and relatively narrower type of gill. The following description is offered as the species appears to be undescribed.