NEW ZEALAND DESMIDIE.E. 
29 
filaments are very prone to break up into their constituent joints. 
The author is in error in supposing that S. filiforme does not occur 
in Britain : it does, but it is rare. 
The author experiences difficulty, it would appear, in discrimi- 
nating between Micrasterias rotata and M. denticulata : there should 
not be any. Besides the distinctions long since pointed out, these 
two species have extremely distinct zygospores. The former, M. 
rotata , has an orbicular zygospore, covered by elongate, subulate, 
acute spines (thus not very ornate), the latter, M. denticulata has 
a zygospore forming one of the most striking of (large !) micro- 
scopic objects, being beset with not so elongate spines, scarcely 
tapering, and beautifully branched. It resembles thus the zygo- 
spore of Micr. papillifera , but smaller, and of a brighter green. 
It is perhaps more difficult to distinguish between M. denticulata 
and M. angulosa, Reinsch., on the one hand, and M. Thomasiana 
(which appears only probably to occur in New Zealand) on the 
other ; but both these latter appear to be good species. The 
author’s M. ampullacea comes very close indeed to M. Hermanniana , 
Reinsch ; the main differences seeming to be the whole of the 
margins of the lobes being serrated in Mr. Maskell’s form, whilst 
in M. Hermanniana the serratures seem to be absent from the 
lower portions of the sinuses, and its side view also is much more 
inflated ; it seems, however, to be quite distinct from the forms with 
which the author contrasts it. 
Micrasterias (Holocystis) incisa , as depicted by the author, does 
not appear to be “ identical,” as he says, with W allich’s Indian 
form, but it is absolutely so with that of Cleve (in Lund ell’s De 
Desmidiaceis,” Tab. i., Fig. 7), and called M. decemdentata, Nag., 
fi Upsaliensis. In fact, if the two figures were made by the two 
authors from one and the same example, they could not more com- 
pletely accord. It is probable, therefore, that we might be safe in 
regarding this as a good species, and it should, presumably, stand as 
M. Upsaliensis , Cleve (the name of course would merely indicate 
that by Cleve at Upsala it was first detected and discriminated). 
Mr. Maskell’s Euastrum, Fig. 26, seems a truly distinct thing, and 
ought to have its own name, though he would appear inclined to make 
the names E. binale or E. elegans do duty for yet one more besides 
the several not uncommon forms they already are made to include. 
Coming to his Cosmarium-forms, and judging by his figures, 
27, 28, and 29, it seems probable that none of the three forms that 
for a considerable time in these countries had been confused to- 
gether under the name Cosm. margaritiferum , are really (as he 
supposes to be the case) depicted by him, but that the figures 
represent rather forms which are notably larger, and probably more 
akin to Cosm. biretum , C. latum , C. Brebissonii , C. rotundatum 
(? ? ?). The author does not pourtray the appearance of the ver- 
rucae, still less their arrangement ; hence the identity of the three 
figures given remains in considerable doubt. 
Staurastrum avicula must be accounted to be wrongly figured in 
