Maskell. — On New Zealand Desmidiese. 305 



cylindrical median lobes is here well seen, and the divergence of the planes 

 of the processes at the ultimate angles is also clear. The edges, in this view, 

 are smooth. 



Zygospore unknown, but I have seen specimens in early stages of con- 

 jugation (?). 



Length of frond (exclusive of terminal processes), ^i^ inch; breadth, 

 over all, ^ko i^ich ; breadth in side view, -^^ inch ; breadth at constriction, 

 ■do iiich. 



Common. 



This pretty little plant belongs to that section of Micrasterias of which 

 M. crux-melitensis may be taken as the type, a section in which the orbicular 

 or sub-elliptical frond is cut into separate lobes by much wider sinuses than 

 in, for example, M. rotata. M. ampullacea, by its three lobes and the bifid 

 projections at the angles of the terminal lobes, approaches the following de- 

 scribed species : — M. americana, Ealfs ; M. haileyi, Ealfs ; M. morsa 

 variety ^, Wallich (this ought to be M. americana var.) ; and M. maha- 

 buleshwarensis, Hobson. But none of these show the peculiar , flask-like 

 shape of the lobes in my species. In M. americana the lateral lobes widen 

 considerably outwards, whereas in M. ampullacea they narrow rapidly out- 

 wards. In all the others, unless the figures given are inaccurate, the lateral 

 lobes taper at once from their bases, whereas those of M. ampullacea, with 

 their sinuous edges, seem to have their widest part a little distant from the 

 base. M. haileyi has quite smooth edges, without serrations. Dr. Wallich's 

 variety 2 has angular, tapering, strongly spined lobes ; and Mr. Hobson's 

 plant (with its fearful and wonderful name) is altogether different in the 

 shape of the lobes ; and moreover has, according to the description, serra- 

 tions only in the sinuses of the lateral lobes. None of the authors named 

 have given a side view of his plant. 



M. ampullacea, when the lateral lobes are trijid, as in figure 6, tends 

 somewhat towards M. foliacea, Bailey, but that plant is distinctly quad- 

 rangular and otherwise different. 



Dr. Wallich, in describing his species from Bengal, proposes to amalga- 

 mate almost aU the species of Micrasterias, and would probably consider the 

 differences between his variety S and my M. ampullacea as only climatic or 

 accidental. But I would venture to observe that, as remarked above, con- 

 stantly recurring identity of form in large numbers of specimens, obtained 

 under various conditions, must point to something rather more important 

 than mere accidental variety. I would look upon such a difference as bifid 

 or trifid lateral lobes as constituting only a variety (if even it amounted to 

 that) ; but if, in New Zealand, a plant has alivays sinuous flask-like lobes, 

 and, in Bengal, always angular tapering lobes, there is at least great evi- 



39 



