Page:Transactions NZ Institute Volume 15.djvu/327

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give a laterally-grooved appearance to the segment and a minutely undulate appearance to the edge, while the central portion seems longitudinally costate.

In side view each segment is angular-elliptic, the end somewhat truncate; and a broadly rounded inflation is distinctly visible at each side.

End view elliptic.

Length of frond 72 μ; breadth in front view 50 μ; breadth at inflation in side view 37 μ; breadth at constriction 25 μ.

Not common: as yet only from the ditch at Bryndwr, near Fendalton, where Triploceras tridentatum occurs, and very rarely in gatherings from Hawke's Bay.

I had long been puzzled by this plant, and had come to the notion that it might be a new species. But my English gatherings from Mr. Joshua have been useful here. One of them is labelled, "C. speciosum var. biforme, Nordstedt," and seems to contain scarcely any other Desmidieæ; and the European plant appears to correspond closely with ours. The differences are, that in the New Zealand plant the central inflation is quite distinct, especially in side view, and the ends are either round or only compressed very slightly, in front view. I rather think also that the granules are smaller than in the English form.

I have met with no description of the European C. speciosum. Neither Ralfs, Rabenhorst, nor Pritchard mentions it; and the only reference which I have found in Professor Nordstedt's papers is a statement that it occurs very sparingly in the Sandwich Islands.

The term "biforme" attached to my English specimens refers, I presume, to the fact that some of them approach in outline rather to C. botrytis.

C. cyclicum Lundell, var. ampliatum, var. nov.

Fig. 7.

Frond in front view orbicular, each segment being about twice as broad as long. Constriction linear, not deep, gaping. Segments when empty showing a number of minute semi-orbicular granules, arranged in rows radiating from the centre, so as to give a grooved appearance to the frond and an undulate appearance to the edge. The ends are not at all compressed.

End view elliptic: the edge undulate.

Diameter of frond in front view, either way, about 50 μ: breadth at constriction 25 μ.

Rare: as yet only from a ditch on the Sumner Road, near Lyttelton, in company with Penium margaritaceum.

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