Since my first communication to the Linnean Society on the subject of freshwater Rhizopods, in 1901, I have had the opportunity of examining a considerable amount of material from some of the outlying districts of the British Isles, and several animals of this class have come under my notice concerning which I can find no previous mention. Two of these are undescribed species of the genus Hyalosphenia, one is a species of Sphenoderia with a prettily constructed shell, and another is a strange nude form referable to Cienkowski's genus Nuclearia. Rhizopods are almost cosmopolitan in their distribution, and few animals exhibit a wider range of variation. In many cases it is almost impossible to define clearly their specific differences, and little attention has been given in the past to the study of the variation of the more abundant forms.