(In 1889 and 1890, Mr. William Sheraton, of Wycliffe College, Toronto, collected some Odonata at Pictou, Nova Scotia, for me. At the end of the collecting season of 1889, he sent me a letter containing his field notes on the specimens captured. These observations are so interesting, in my opinion, that any publication in which they appear ought also to bear Mr.Sheraton's name as joint author. He has kindly acceded to my wish in this respect, although modestly protesting that his part has “been only such as any child could have done.” All notes in the present paper concerning localities, habits and dates are to be credited to Mr. Sheraton, while I am responsible for the determinations and the few bibliographical notes.)