Maskell. — On the New Zealand Desmidieaa. 245 



At first sight this plant might be taken, in side view, for 8. spinosum, or 

 in end view for S. monticulosum, Brebisson. But it differs from the former 

 in having its outer edges less turgid than the inner and in its processes not 

 being on the same plane ; from the latter in the more cylindrical lateral 

 processes and then- forked tips. The nearest resemblance to it is, I think, 

 S. (Desmidium) eustephanum, Ehrenberg, an American plant, referred to by 

 Balfs, p. 215, without figure, and described and figured in Pritchard's Infus., 

 p. 743 and pi. ii., fig. 3. The differences are that in the New Zealand 

 plant the sides, in end view, are emarginate and not rectilinear as in the 

 American variety, and the lateral processes project beyond the sides, 

 whereas in Pritchard's figure they are very small and do not reach the 

 sides. In 8. senarium, Ehrenberg (also American), similar processes pro- 

 ject, but there is also a second series of six others, shorter and in almost 

 corresponding directions, behind the first. In the " Midland Naturalist," 

 vol. iv., pi. v., Mr. A. W. Wills figures 8. pseudofurcigerum, Eeinsch, not 

 unlike our plant in end view, but it is covered with minute spines on the 

 processes as well as on the frond, and the side view is also different. 



On the whole, I take this plant to be intermediate between S. eustepha- 

 num and S. senarium. 



S. clepsydra, Spencer (in lit. cum specim.), sp. nov. S. 



Fig. 12. 



Frond somewhat large, smooth. Segments in side view broader than 

 long, widening rapidly from the constriction which is not deep. The ex- 

 ternal edges are either straight or oftener slightly concave : lateral edges 

 convex. Ultimate angles ending in a fine awn or mucro. In consequence 

 of the shallow constriction the segments are closely united at the base, the 

 junction is broad, and there is no isthmus or band whatever. The apex of 

 the third angle with its awn is usually visible beyond the external edge of 

 each segment. 



Frond in end view triangular ; the sides equal, slightly concave : some- 

 what mammillate at the angles which are terminated by the awns. The 

 concavity of the sides is not always conspicuous. 



Frond quite free from puncta. 



I have seen no zygospores attached to fronds, but in every gathering 

 there are a number of bodies which may not improbably belong to this 

 plant. They resemble generally those of S. dejectum, but have fewer spines. 

 I have been able to compare them not only with Balfs' figures of 8. dejec- 

 tum, but also with zygospores of that species in my English gatherings. 



Length of frond in side view 31-40 p ; breadth at external edge of seg- 

 ments (exclusive of awns) 30-35 p; breadth at constriction 15-17 p; side of 

 triangle in end view 30-35 p ; length of awn 5 p. 



