30 
NEW ZEALAND DESMIDIE/E. 
Balf’s Br. Desm. ; it is apparently not a smooth species, but rough ; 
the author’s figures, 31, 32, hardly accord with the form met with 
in these countries, and may possibly represent a distinct form. 
The author accepts the genus Didymocladon as distinguished from 
Staurastrum, but there appears to be no tenable grounds for this 
course ; those Staurastrum-species with two arms or processes, one 
vertically superposed over the other, at each angle, need no more a 
separate genus than those other Staurastra likewise with super- 
posed processes, two over one, but those divergent at each side, or 
those again with two processes only at each angle, but placed side 
by side on the same horizontal line. The author’s Didymocladon 
stella seems to be doubtless Staurastrum sexangulare, Bulnheim, a 
species not very aptly named, for, as a rule, the examples occurring 
in these countries (at least in Ireland) are but five-angled, and here 
is a New Zealand form with seven angles ; also, four, five, six, and 
seven angled forms occur in Sweden. Mr. Maskell’s plant appears, 
notwithstanding, on the whole rather smaller, however, than the 
European form, and the rays rather more slender — whether a 
minute submarginal series of granules in the sinuses seen in 
end view occurs in the New Zealand examples does not appear. 
The beauty of this fine and rare form is somewhat marred by the 
density of the mucous envelope that usually accompanies it, at 
least in Irish specimens. It has been lately found by Mr. Wills in 
North Wales. 
The author’s Docidium dilatatum is doubtless the same thing as 
Docidium ovatum , Nordstedt, first found in collections from Brazil ; 
it is very interesting to find it reappearing in New Zealand. 
Triploceras bidentatum, Maskell, is a very noble new species, and 
seems very distinct indeed. 
So also is the remarkable Closterium selenceum, Maskell, a form 
unique in its shortness and plumpness, and in its relative propor- 
tions and its curvature. It is a pity the author colours his figures 
with so much uniformity — doubtless this fine Closterium will 
present more or less of the Closterium-fashion in the arrangement 
of the contents, but it is figured in this respect with a homo- 
geneous green colour, and evenly distributed amylaceous (?) 
granules, precisely similar to the uniform mode incorrectly shown 
for the Docidium, the Staurastrum, and the Cosmarium forms, all 
which are really, in this regard, mutually very diverse ; nor is the 
shade of green employed that of the grass-green of most Des- 
midiese ; but the outlines are without doubt very true to nature. 
Touching Closterium setaceum and Cl. rostratum, these appear 
distinguishable as they occur with us, but the distinction between 
the former and one or two of de Brebisson’s ((7. elegans , C. Kiit- 
zingii ) do not appear so decided. 
Both the forms of Ankistrodesmus recorded, but not named by 
Mr. Maskell, occur in these countries ; one, that in which the cells 
forming the bundle stand parallel, but not apposed, in groups, 
seems well marked ; it is not at all common. Neither these forms, 
