MasxkEnr.—On the New Zealand Desmidies. 251 
I have already mentioned that this plant, which was common here two 
years ago, has been very scarce of late: and no sign of conjugation has as 
yet come under my observation. 
Holocystis incisa. 
-Mr. Archer unites this to Micrasterias (other authors, I find, include it 
under Tetrachastrum) ; and he states that instead of being identical, as I had 
thought, with Dr. Wallich's Indian plant, it is probably the same as a plant 
from Sweden, reported by Cleve and called M. decemdentata B upsaliensis. 
Kuastrum binale, Turpin. 
The plant mentioned by me (vol. xiii., p. 306) as either this or E. legate 
is certainly E. binale, as I have satisfied myself by comparison with Ralfs’ 
figures, and with specimens in my English gatherings. Æ. elegans shows 
the sides of the terminal notch extending considerably beyond the lateral 
spines. I regret to say that the figure 26 in vol. xiii., pl. xii., is about as 
unlike the plant which it is supposed to represent as it is possible to be ; 
and unluckily Mr. Archer has been misled by it to take my Huastrum for a 
new thing. . My original drawing was meant to be, and I think was, almost 
exactly resembling Ralfs’ figure 8 d (or 8 f) in his pl. xiv. 
Cosmarium margaritiferum. 
I believe that several of the forms supposed by me to belong to this 
species were really C. tetraophthalmum, C. broomeii, etc., or at least closely 
allied to them. C. biretum I have never seen here: C. botrytis is certainly 
common. The conjugation of C. margaritiferum I saw once, and could detect 
no difference from the European plant. In this case also the printed figures 
in pl. xii., vol. xiii., figs. 27, 28, and 29, are unsatisfactory. Fig. 28 was 
intended to show a slight truncation, but it does not show any. 
Cosmarium crenatum, Ralfs. 
Fig. 15. 
If Ralfs’ figure 7, pl. xv., be correct, our New Zealand form differs 
from the English one by having its ends (as my figure shows) straight, 
without crenations. I think also that the segments are somewhat wider at 
the base. Length of frond 80:5 p; breadth 27 p. 
Cosmarium botrytis, Bory. 
In examining this plant I have been able to detect a very decided volun- 
tary motion, which on one occasion I observed for nearly three hours. As 
far as I can gather from works available to me, it has never been satisfac- 
torily shown that the Desmidiex travel voluntarily, that is, in the manner 
in which Diatoms travel. It has long been known that Désmids ‘‘ move ;” 
that is, they will come to the surface if buried in mud, or to the side of a 
vessel nearest to the light. But such movements as these, as Ralfs remarks 
(p. 22), may be due rather to the stimulus of light than to ‘ voluntary 
