During the past few years I have been collecting and examining from every possible situation numerous small plants belonging to the Algae, and amongst them I have found Rhizopods and Heliozoa in abundance. Most of the interesting forms of these groups I carefully sketched, in some instances making detailed and extended examinations of them, and I now possess an accumulation of notes and drawings, many of which may be deserving of notice. Some of the observations in this paper relate to the habits and structure of certain of the Rhizopods and Heliozoa; others are descriptive of peculiar forms of the commoner and more abundant species; and others again are records of rarer and less-known species. I also give descriptions and figures of six animals which I believe have not previously been observed, one of which I have referred to a new genus (p. 325). A point of considerable interest is the presence of a perforation at the apex of the shell of some forms of Difflugia acuminata, Ehrenb. The shell thus possesses two openings, one at each end, as in the case of those Rhizopods referred to the family Amphistomina.