Maskell. — On Neio Zealand DesniidieEe. 5 



Wills, A. W. On the Desmidieas of North Wales (in "Midland Na- 

 turalist"). 1881. 

 WoLLE, F. Desmids of the United States. 1884. 

 Fresh-water Algaj of the United States. 1887. 



Also detached papers on Desmidie^ and other Alg.'B by Nordstedt, 

 Wittrock, I\Iarquand, and others. 



Professor Nordstedt's paper on the New Zealand Algce, 

 included in the above list, is specially valuable. It contains 

 descriptions, with seven plates, of about one hundred and fifty 

 species and varieties of Desmidlece. 



I have to make the following remarks and corrections 

 regarding some of the plants included in my two former 

 papers. These are rendered necessary by more accurate 

 knowledge acquired since 1882, either by observation, or by 

 more extended access to the literature of the subject, or by 

 suggestions from Professor Nordstedt, Mr. Turner, and 

 •others. 



Aptogonnm undulatum ("Trans. N.Z. Inst.," vol. xiii.). 

 The genus Aptocjomim is now by most writers considered as 

 properly only equivalent to Desviidiinn, Agardh ; and Profes- 

 sor Nordstedt attaches my plant as a variety to D. hailcyi, de 

 Bary. In his description and figures ("Alg- of N.Z.," p. 27, and 

 pi. ii., 8) he does not, I think, express altogether the convex 

 curve of the upper portion of each cell as seen in front-view 

 (or, as I called it in 1880, the "side-view," meaning as in 

 filament). His specimens appear to be more angular than any 

 I have seen, and I have re-examined for comparison a number 

 of preserved specimens and a few fresh ones. Also, he states 

 that in all cases the end-view is " regularly triangular, with 

 rounded angles and almost straight sides." I find that this is 

 so as a rule ; but several specimens exhibit an end-view 

 similar to that given in my paper of 1880 (vol. xiii., pi. xi.), 

 except that the printers then added a sort of loop or curved 

 open ring, which was not in my original drawing, and instead 

 of which there should have been only the three small processes 

 near the angles. 



Micrastcrias rotata (vols. xiii. and xv.). This, which I 

 reported with very great doubt in 1880 and 1882, turns out to 

 be j\I. scliKeinfurthii, Cohn, a Central African plant. ]\Iy 

 fig. 166 (vol. XV.) is a form of M. angulosa, Hantzsch. 



Euastrum hinale, forma (vol. xiii.). The fig. 26 in pi. xii. 

 is the variety denticulatum, Kirchner. See the present paper, 

 with more accurate figure. (PI. II., fig. 12.) 



Holocystis incisa (vol. xiii.). This is Micrastcrias deccvi- 

 dentata, Naegeli, var. upsaliensis, Cleve. 



Cosmariuvi ralfsii (vol. xiii.). This is very near to C. 

 'pseudopachydermum, Nordstedt ("N.Z. Alg.," p. 53), and is not 



