238 Transactions.— Botany. 
tetraophthalmum, Closterium acerosum, Clost. lineatum, Penium margaritaceum, 
and afew more. Still, conjugation seems to bé very rare here, and Dr. 
Spencer tells me that it is equally so in Hawke’s Bay. By the way, it is 
curious how capricious the Algæ often seem to be in their appearance and 
disappearance. For example, two years ago, Micrasterias rotata and M. 
ampullacea swarmed in some pools. This year both are exceedingly scarce 
about Christchurch. Volvos globator was to be found, in 1878 and 1879, in 
myriads: since then I have seen very few, and during the last twelve months 
not a single specimen. 
It will be observed that, with the help of the Hawke’s Bay gatherings, I 
have been able to add three genera to the New Zealand Flora, viz., Desmi- 
dium, Xanthidium, and Arthrodesmus ; but I have not found any of these in 
Canterbury. 
The measurements adopted in this paper are expressed in the modern 
nomenclature which, as I understand, microscopists in Europe are endea- 
vouring to bring into general use. Instead of the old “ inch," and 
fractions of it, which were only intelligible to Englishmen, micro-measure- 
ments are now expressed by the symbol p, representing a micro-millimetre. 
e p = topo millimetre = z5000 inch almost: so that, for example, 
instead of saying that Micrasterias rotata has a length of 1, inch, one would 
say nowadays 278 u. This mode is intelligible to observers of all coun- 
tries, and is undoubtedly preferable to the old one, 
I regret to say that a little ditch near the Fendalton Road, which has 
supplied me with some of the most curious of the New Zealand Desmids, 
including Triploceras tridentatum, Staurastrum aculeatum, and others, will 
soon be no longer available. At the best it was only a little ** grip" in a 
field, almost dry in summer; and it was always a puzzle to me how so 
many uncommon forms got there, especially as it could not have existed 
many years. But now the march of progress is rapidly effacing it, and the 
streets of the flourishing village of Bryndwr will probably in a few weeks 
destroy it altogether. The worst of it is that I know no other habitat in 
Canterbury for some of these forms. 
Parr I, 
Additions to Catalogue of New Zealand Desmidies. 
1, Desmidium, Agardh. 
D. swartzii, Agardh. S$. (R. IV. : 
Not uncommon, apparently, in Hawke's Bay. It has not been found in 
Canterbury. . 
D. aptogonium, Brébisson. §. (R. XXXII.) 
I have not seen this plant, which Dr. Spencer informs me occurs very 
rarely in Hawke’s Bay. 
