The Rocky Mountain Species of the Mayfly Genus Ephemerella.

Ever since the publication in 1884 of that part of Eaton's. Revisional Monograph of Recent Ephemeridæ treating of the genus Ephemerella, the Rocky Moutain region has been known as the source of some of the most remarkable of Mayflies. The strangest of these Eaton knew only as nymphs. These he described and figured. The incomplete results of rearings that were published by myself in 1905 and by Dodds in 1923 left matters in some confusion, as was pointed out by Lestage in his comprehensive review of the group in 1925. For some time there has been obvious need of more careful life-history work on these forms, such as could only be done in the place where they live.