Frond rather large; constriction deep, linear; segments in front-view obscurely three-lobed, the basal lobes widely emarginate with very shallow depressions; end-lobe compressed, ends slightly dilated, round, a little protuberant, with a deep narrow notch. At the base of each segment five granuliferous inflations (three on the face and one at each side); above these four others; at the ends an inflation on each side of the notch; altogether eleven inflations on each segment. The granules are conspicuous, and the cytioderm as punctate. Segments in side-view thick, sub-cylindrical, slightly narrowed near the ends, the inflations giving irregular outlines. In end-view the sub-elliptical grooved ends appear conspicuously on the rounded and inflated basal lobes, the granules being conspicuous.

Long., 75–80 μ; lat., 40–44 μ; crass., 26 μ; lat. isthmi, 11.8 μ.

Hawke's Bay; Otaki.

B. Forma minor, var. simplex, var. nov. Plate I., fig.6.

Frond much smaller than the last; otherwise similar in outline. Inflations not constant in number: some plants exhibit eleven on each segment, others only seven, the lowest row having only three, the middle only two; inflations granuliferbus, the granules distinct. Cytioderm smooth, or, at least, the puncta are extremely obscure. Zygospore globose, with subulate spines which have very broad bases and rather long points.

Long., 53 μ; lat., 26 μ; diam. zyg. ex spin., 27 μ; long. spin., 11 μ.

Rutherford's Swamp, Otaki.

E. sinuosum was attached by Ralfs (“Brit. Desm.,” p. 85) to E. circulare, Hassell, but has since been considered as separate. The two forms here given do not, as it seems (unless the hitherto undescribed zygospore of the European plant be found to differ), require to be considered as anything but varieties of the type. Nordstedt reports (“N.Z. Alg.,” p. 33) E. sinuosum from New Zealand without remark. The measurements which he there gives (long., 87 μ; lat., 50 μ) are a good deal larger than those of Ralfs. My var. gemmulosum exactly corresponds with Ralfs's dimensions; the var. simplex is a good deal smaller. The measurements I give are constant in a number of specimens observed. I think that the conspicuous granules in the inflations of both, the divided sub-elliptical end conspicuous in end-view, and the shallowness of the depressions in the edges, may be taken as sufficiently distinctive characters: the variable number of inflations is not important. Wolle (“Desm. of U.S.,” pl. xxvii.) figures E. circulare with much-compressed end-lobe, and with a

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-

angular. Inflations doubtful, no specimen having been seen without endochrome.

Long., 11.4 μ; lat., 13.2 μ; crass., 3.2 μ.

Christchurch.

If it were not for the concave ends and for the appearance in end-view, this plant would belong more properly to the genus Cosmarium. It is exceedingly minute, and not common.

* Euastrum denticulatum, Kirchner. Plate II., fig. 11.

This appears to be one of the innumerable varieties of E. binale, Ralfs. It is the plant of which a rough representation was given by me in 1880 (“Trans.,” vol. xiii., pl. xii., 26):. the present figure is more accurate. Nordstedt (“Alg. of N.Z.,” pl. iii., fig. 11) represents this plant as “sp. ad E. denticulatum accedens,” and in his fig. 9 he shows Kirchner's original type as a good deal smaller. The two sizes occur here together. I can detect only one median inflation on each segment in front-view. The side-view which I give is less “ornate” than that of Nordstedt (iii., 11c): it is taken from two specimens observed.

Hawke's Bay; Christchurch.

Euastrum binale, Ralfs, forma. Plate II., fig. 12.

This seems to be nearer than the last to the original type, although it does not seem to fit it exactly.

Christchurch.

The variations of E. binale would appear to be endless. Ralfs, Lundell, Delponte, Wolle, all give figures which differ a good deal from each other. Especially Wolle describes and figures E. binale as distinguished by the “pouting” of the ends at each side of the terminal notch, this very character being a distinctive one of E. elegans. In fact, there is so much difference in these figures that one wonders why some of the plants have not been transferred to other species. My figure 12, which I take to be E. binale because its ends do not exhibit any “pouting,” is very similar to one of Wolle's exhibit any “pouting,” of U.S.,” pl. xxvii., 25) which he names E. elegans.

Euastrum undulosum, sp. nov. Plate II., fig. 13.

Frond moderate; constriction deep, linear; segments in front-view trapezoidal, tapering directly from the base to the rather wide ends; sides crenate, each with four equal crenations; ends wide, angles divergent, with minute terminal spines, slightly protuberant towards the middle and emarginate; notch conspicuous; at the base of each segment is a single median conspicuous inflation, and on the face of the frond a number of concentric verrucose undulations. In side-view the constriction is shallow and wide, the inflation visible;