254 Transactions. — Botany. 



Staurastrum avicula, Br^bisson. 



Mr. Archer thinks that our plant may be a distinct form and says that 

 Bali's' figure of the English species is incorrect. I am willing to accept 

 this, but as I have not seen any specimens since writing my former paper I 

 am not prepared to suggest any new name. 



All these minute forms of Staurastrum are difficult of identification and 

 it would be easy to multiply species upon the slight differences occurring so 

 frequently. 



Didymocladon Stella, mihi. 



This plant must, I suppose, be relegated to the genus Staurastrum, as 

 Pritchard, Eabenhorst and succeeding writers do not admit Kalfs' genus. 



As to its specific status, I am in some doubt. After carefully compar- 

 ing it with specimens of S. furcigerum, both from Hawke's Bay and from 

 England, and allowing for Babenhorst's statement that S. furcigerum may 

 have from three to nine rays in end view, I cannot regard my S. (Didymocla- 

 don) stella as identical with that plant. In all my specimens of S. furcigerum, 

 as remarked in the first part of this paper, whether there are five or six 

 rays, those rays which are behind the terminal ones, and which are at first 

 sight out of focus, are always in almost, if not quite, direct correspondence 

 of direction with the terminal rays. I cannot see how in any case the pecu- 

 liar multi-radiate appearance of S. stella can be produced by the English 

 plant. 



I find, however, in the "Midland Naturalist," a figure (vol. iv., pi. v.) 

 of Staurastrum arctiscon, Ehrenberg, a plant mentioned by Eabenhorst as 

 American, under the name Xanthidium arctiscon, and seemingly found 

 lately in Wales. This plant, in end view, has six terminal rays, and eight 

 others behind them, almost in corresponding directions. Whether, in some 

 cases, it may show the twenty-eight divaricating rays of my S. stella I can- 

 not say : if so, my plant will have to be abandoned as a distinct species. 



S. pseudo-furcigerum, Beinsch, though its side view approaches best to 

 that of S. stella, differs altogether in end view, being then more like S. 

 eustephanum in general outline. 



I find that Mr. Archer would refer our plant rather to Staurastrum sex- 

 angulare, Bulnheim, which I do not know. 



Docidium baculum, Ehrenberg. 



I expressed in my former paper doubts as to the existence of this plant 

 here, and after comparison with English specimens I have come to the con- 

 clusion that it is not found here, or at least that it has not come under my 

 notice. Its distinctive character is the possession of a solitary, prominent 

 inflation at the base of each segment. All my New Zealand specimens 

 show at least more than one inflation. 



