OF the Infusoria, of which camera drawings are laid before you, I purpose giving such brief descriptions as may be necessary for their explanation. I.—Fig. 1. A Difflugia of small size—1/300th—with smooth, very transparent chitinous test, flattened beneath, rounded above, with circular, smooth, direct aperture, through which the sarcode flows in a feeble undivided stream, containing very minute, greyish granules. From the posterior part of the bottle-shaped body four filamentary diverging ligatures stretch to the fundus of the test, binding down and securing the animal in its suspended position. These filaments—extensions of the pellicular investment—have, I think, a peculiar interest, not only as the sole example known to me of such a structure among the fresh-water Rhizopoda, but as demonstrating a fact in the Difflugiæ at least, as much disputed as admitted in the cognate naked Amœbæ of such a surface differentiation from the internal fluid sarcode, as may unquestionably be considered as distinctly cuticular.