In my paper on the Ephemeroptera of Covel Hill, Que., I recorded the spccies E. dorothea Needham as extremely common. In the summer of 1927 my assistant, Mr. G. S. walley, took numerous full-grown nymphs in the Covey Hill brook at a time when the so-called dorothea were emerging, so that the association of nymph and adult is fairly safe. These nymphs, however, proved to agree excellently with the description of cornuta Morg. except for the somewhat smaller size, and a careful reading of Dr. Morgan's description of the male subimago (the only other stage known to her) made it evident that the Covey Hill species should be known as cornuta Morg. and not dorothea Needh.