248 Transactions. — Botany . 



S. acutus, Meyen, var. dvmorpkus, Kiitzing. (K. XXXI.) 



The cells are pointed, closely arranged in a single even row and the two 

 outer ones are lunate. 

 Not common. 



S. obtusus, Meyen. (K. XXXI.) 



The cells are ovate or oblong and not in an even straight row. 

 Common. 



Paet II. 

 Notes on some of the Desmidiea described in my former paper.* 

 I have had the advantage lately of perusing, in vol. x. of " Grevillea," 

 No. 53, Sept. 1881, an article by Mr. Archer reviewing my paper on New 

 Zealand Desruidiea3. 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 thinkiug that there is great reason 

 to believe many of the Desmidiea3 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 in 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 Gosmarium, 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. 



