the segments taper with sinuous edges to the rounded ends. End-view sub-elliptical with median inflation. Cytioderm very obscurely punctate, if not free from puncta. Long., 38.6 μ; lat., 22.7 μ; crass., 13.5 μ. Hawke's Bay. E. incrassatum, Nordst., is more elliptical, and has not dilated ends; also its crenations are not equal. E. crenatum, Kützing, seems near it; but Dr. Bennett (“Journ. Roy. Micros. Soc.,” 1886, p. 9) describes that plant as having quite straight ends and scarcely any notch; also a very shallow constriction. It differs from E. denticulatum in the absence of the rather deep notch which in that species separates the terminal from the lateral lobes. In E. undulosum the edge is evenly crenulate from the constriction to the terminal angles. Euastrum irregulare, sp. nov. Plate II., fig. 14. Frond small; constriction deep, linear; segments in front-view sub-trapezoidal, the sides tapering from the base to the rather wide ends; ends emarginate, with conspicuous notch, the lips of which do not protrude; at the angles fine spines; sides irregularly emarginate, incised with small but distinct depressions, but the division between the terminal and lateral lobes is not clearly marked. Inflations on each segment in front-view seven—three at the base, two at the end, and two near the sides. In side-view the segments are sub-rectangular, slightly inflated towards the base, the ends very slightly dilated, with rounded angles. End-view sub-fusiform, with sinuous edges. Long., 22.3 μ; lat., 18 μ; crass., 8.9 μ;. Kaitoke; Otaki; Masterton. In outline this plant is similar to some varieties of E. binale, except that the edges are much more irregularly incised; the number and arrangement of the inflations also differentiate it. Genus Cosmarium, Corda. Cosmarium variabile, sp. nov. Plate II., fig. 15. Frond moderate, elongated; constriction shallow, rather open; segments tapering from rounded basal angles to rather wide truncate ends; sides sometimes convex, sometimes straight, sometimes concave; ends very slightly rounded or almost straight, never concave, but with often the inner cell-wall distinctly thickened. The cytioderm is not punctate. In side-view segments elliptical, ends more or less acute, sides smooth. The end-view is elliptical. Long., 42 μ; lat., 21 μ; crass., 15μ. Hawke's Bay; Otaki.