circular end in end-view. He gives its length as only 36 μ, and does not mention E. sinuosum. * Euastrum longicolle, Nordstedt. Plate I., fig. 7. There is in this plant, near the middle of each segment in front-view, a small circular orifice with a spot in the centre, as if there were there a ring-like opening of the frond. Professor Nordstedt (“N.Z. Alg.,” p. 33) casually mentions this feature without further remark. The only other species of this genus, as far as I am aware, exhibiting “scrobiculi” are E. crassum, var. scrobiculatum, Lundell, and E. rostratum, Ralfs, var. præmorsum, Nordstedt, the former a Swedish, the latter a New Zealand form. Rutherford's Swamp, Otaki. Euastrum rotundum, sp. nov. Plate I., fig. 8. Frond moderate; constriction deep, linear; segments in front-view obscurely three-lobed, the basal lobes smoothly and widely rounded, not emarginate; on each segment three basal granuliferous inflations, and two others at the ends; a few granules on the edges. Segments in side-view sub-cylindrical at the base, slightly emarginate on account of the median inflation, then tapering rapidly towards the ends, which are very slightly dilated. End-view elliptical with median inflation. Long., 44.6 μ; lat., 26 μ; crass., 17 μ. Rutherford's Swamp, Otaki. Allied apparently to E. pingue, Elfving; but it is more slender and less clearly three-lobed. It is much smaller and more evenly rounded than E. ansatum, Ralfs. E. obesum, Joshua (“Burm. Desm.,” p. 638, and pl. xxiii., 19), is like it in outline, but is larger as a rule, and has apparently no granuliferons inflations. *Euastrum sublobatum, Brébisson. Plate I., fig. 9. Some authors place this plant under Cosmarium, others under Euastrum. The end-view seems to me to determine its place in the latter genus, and so I leave it. Hawke's Bay. Euastrum expansum, sp. nov. Plate I., fig. 10. Frond very minute, not quite as long as broad; constriction deep, linear, rather wide externally; segments in frontview three-lobed, basal lobes somewhat protruded and a little turned upwards, end-lobe with concave end but without a terminal notch. Frond in side-view narrow, constriction shallow and wide, segments elliptical towards the base and tapering towards the rounded ends. End-view elliptical at the base, with the tip of the end-lobe appearing as if sub-rect-