Additions to Catalogue of New Zealand Desmidieæ. [Note.—Plants marked with an asterisk (*) have been reported by Professor O. Nordstedt, in his account of fresh-water Alga collected in New Zealand by Dr. S. Berggren.] Genus Sphærozosma, Corda. Sphærozosma compressum, sp. nov. Plate I., fig. 1. Plant filamentous; joints very minute, elongated, the ends orbicular, the middle cylindrical and compressed, each joint having the appearance of a dumb-bell. Filament twisted, the joints in side-view less compressed in the middle. Section elliptical. Endochrome chiefly visible in the cylindrical portion of each joint. Zygospore smooth, orbicular, a good deal wider than the joints. There are no processes between the joints, of which there are sometimes at least thirty in a filament. Long. cell., 10.7 μ; lat. term., 5.8 μ; lat. med., 3.5 μ; diam. zyg., 8.8 μ. Rutherford's Swamp, Otaki. This plant is allied to S. excavatum, Ralfs, but differs in the cylindrical middle, orbicular ends, generally longer and rounder joints, and absence of connecting processes. It seems to be rare. *Sphærozosma pulchellum, Archer. Plate I., fig. 2. Approximating to S. bambusinoide, Wittrock, which Wolle considers as a variety of S. pulchellum. Sphærozosma formosum, sp. nov. Plate I., fig. 3. Cells almost twice as long as broad; filament not twisted; constriction rather deep, linear within and wide at the mouth; semi-cells roundly inflated at the base, thence sub-cylindrical to the rounded angles of the ends, which are not at all dilated; ends straight or slightly convex; cells joined to each other without any glands or processes. Cytioderm smooth. End-view elliptical or sub-circular. Long. cell., 22.5 μ; lat., 13.4 μ; crass., 10.5–12 μ. Hawke's Bay. Like most species of this genus the filaments are very fragile. I have seen a few with as many as twenty or more joints; but it is rare to find more than three or four cells together, and in most cases the joints are single. When single these cells may easily be taken for Euastrum sublobatum, which is nearly of the same size; but in that plant the terminal angles are slightly dilated, the ends are concave, and the end-view is different. Sphærozosma formosum is so much larger than S. pulchellum, and its cells are so much less inflated (proportionately), that it must for the present be con-