I have received from Mr. H. G. Hubbard some larvæ and pupæ, with the case, labeled as follows: “The Simulium larvæ and pupæ were collected on the rocks at the foot of the fals of Michipicotin River, Lake Superior, in shallow pools and gutters of rapid water. There were large patches of rock suriace densely covered with either the larvæ or pupæ, so closely packed as to resemble a growth of aquatic vegetation. The black flies were very abundant in the woods.”