In the present paper, besides descriptions of a few species which appear to be undescribed, I offer some critical notes on certain statements made and conclusions arrived at by Dr. Jay Traver in the taxonomic portion of Needham's Biology of Mayflies. The proof of the pudding is in the eating, and the value of a work such as the above can only be ascertained by constant checking of the keys and descriptions in connection with the examination of typical or topotypical material.