Page:Transactions NZ Institute Volume 15.djvu/323
2. Sphærozosma, Corda.
S. pulchrum, Bailey. S. (R. XXXV.)
Occurs in Hawke's Bay, rarely. I have not seen it. Mr. Archer (in Pritch. Inf., p. 724) includes this plant in the genus Spondylosium, as it has no processes uniting the joints. Rabenhorst considers Spondylosium only a sub-genus of Sphærozosma.
3. Euastrum, Ehrenberg.
E. ansatum, Ehrenberg. S. (R. XIV.)
Not uncommon. From Hawke's Bay.
4. Cosmarium, Corda.
C. ralfsii, var. β, var. nov.
Fig. 1.
Differs from the normal form only in its size, which is very small. Length in front view, 37.5 μ; breadth, 25 μ. But these dimensions are quite constant, and the larger form has not been present with it in any gathering which I have observed. Were it not for the slightly triangular segments it might be C. cucumis; it cannot be C. pyramidatum, as the frond is smooth.
C. thwaitesii, Ralfs. (R. XVII.)
Fig. 2.
Rare.
I am doubtful about this plant, as I find no trace whatever of any gelatinous covering, whether for single fronds or colonies. Ralfs says of it, "puncta very indistinct:" the plant here is smooth. Length, 44 μ.
C. pusillum, Brébisson.
Fig. 3.
This is the smallest plant of the genus known to me. I copy Mr. Archer's description (in Pritch. Inf., p. 731): "Frond very minute, slightly broader than long, constriction acute, segments angulato-trapezoid, slightly narrowing upwards, smooth, angles rounded, ends slightly concave." I think, however, that the plant here is punctate. The plant is scarcely visible below a power of 200 diameters. Length of frond, 12 μ; breadth, 15 μ.
Hitherto described only from France (Brébisson) and Saxony (Rabenhorst).
Not common. I have specimens dividing, but no zygospores.
C. punctulatum, Brébisson.
Very similar to a young state of C. margaritiferum: indeed Mr. Archer (in Pritch. Inf., p. 733) unites the two. Rabenhorst is doubtful on the point.
Common, both in Canterbury and Hawke's Bay.