and certainly the number of small crenulations on the margin is about double that of Lundell's plant, which has only twelve. The rather widely-gaping constriction (from which I took my former name) seems to separate it from any species hitherto described. Long., 51 μ; lat., 46–49 μ; crass., 16 μ. Sumner Road, Lyttelton. Cosmarium heliosporum, sp. nov. Plate III., fig. 30. Frond small; segments in front-view sub-quadrate, crenate, with from ten to twelve conspicuous crenations; angles rounded; cytioderm marked with large granular inflations corresponding to the crenations and radiating from the median space, giving the frond a deeply-grooved appearance; in the median space, at the base of each segment, a row of small, apparently vertical inflations, usually five in each row. In side-view, segments sub-quadrate, slightly tapering to the wide ends, which are a little convex; edges smooth at the base of the segments, and minutely crenulate at the ends. End-view elliptical, with transverse rows of granules; viewed from the base of a segment the granules form a circle round the isthmus. Zygospore globose, with numerous spines; the spines subulate, on broad bases, and minutely divided at the apex. Long., 28.3 μ; lat., 23 μ; crass., 15.6 μ; diam. zygosp. exclus. spin., 33 μ; long. spin., 3.5 μ. Hawke's Bay. A species belonging to the series of C. crenatum, but distinct by its sub-quadrate segments, which are conspicuously crenate at the ends, and by the form and size of the spines on the zygospore. From these spines Mr. Turner suggested to me the specific name which I have herein adopted. *Cosmarium amplum, Nordstedt. Plate III., fig. 31. I give a figure of this plant, partly because of its peculiar end-view in some cases (roundly triangular); partly because the granules seem to me often to be arranged in concentric curves, and not always in quincunx, as Professor Nordstedt reports; and partly on account of a conspicuous inflation, observed in some specimens when viewed neither in. front nor directly from the end. The plant is a fine one. Perhaps two-thirds of the specimens observed by me from Otaki have a triangular end-view; all those from Hawke's Bay have elliptical ends. Hawke's Bay; Otaki. Cosmarium quadrifarium, Lundell, var. gemmulatum, var. nov. Plate III., fig. 32. Frond moderate; constriction deep, linear; segments in