248 Transactions.— Botany. 
S. acutus, Meyen, var. dimorphus, Kützing. (R. XXXI.) 
The cells are pointed, closely arranged in a single even row and the two 
outer ones are lunate. 
Not common. 
S. obtusus, Meyen. (R. XXXI.) 
The cells are ovate or oblong and not in an even straight row. 
Common. 
Parr II. 
Notes on some of the Desmidiee described in my former paper.* 
I mave had the advantage lately of perusing, in vol. x. of ‘ Grevillea,” 
No. 58, Sept. 1881, an article by Mr. Archer reviewing my paper on New 
Zealand Desmidiese. It has been a great satisfaction to me that so acknow- 
ledged an authority does not find grave fault with the descriptions which I 
gave of my new species, nor, in general, with the paper itself; and Mr. 
Archer's remarks have gone far to clear up some points upon which I have 
been in doubt. I take this opportunity of referring again, in a more or less 
explanatory way, to some of the plants therein mentioned, as well as to 
some others that Mr. Archer makes no comment upon. 
Previously, however, I must touch upon a point referring to the whole 
family. Mr. Archer agrees with me in thinking that there is great reason 
to believe many of the Desmidiew to be cosmopolitan, but he goes on to 
remark that my “ identifications of certain species may not be thoroughly 
correct.” The same thought was certainly in my own mind when writing 
my paper; and iù my introductory remarks I observed that “in many of 
the species which I have set down here as European, more especially 
perhaps in the genus Cosmarium, I have noticed peculiarities which do not 
seem to have been mentioned by authors. The discussion of these would 
lead me beyond the scope of this paper and perhaps the characters to which 
I refer would not even suffice to raise the plants even to ‘varieties?’ ” In 
point of fact, three reasons prevented me from attempting to differentiate 
these plants from European species. First, the dearth of works of refer- 
ence, for it was impossible to tell whether the minute characters noticeable 
were referred to or not by any author elsewhere. Secondly, a doubt 
whether these characters might after all only have been overlooked, or 
erroneously referred to, by previous observers ; and an instance of this is 
afforded me in Mr. Archer's paper in ** Grevillea,” where Staurastrum avicula 
is stated to be really, in England, “not a smooth species, but rough,” and 
this was a plant regarding which I expressed doubts in my paper and which 
* Trans. N.Z. Inst., vol. xiii., 1880, p. 297. 
