ARCHER, ON MICRASTERIAS MAHABULESHWARENSIS. PAT 
blances to be sought for and taken into account, I do not see 
any limit to the doing away with any number of species, nor 
to the consolidation of perhaps. a whole genus, or even of 
groups of genera, as single species. Imbued, however, with 
the views which he holds as regards the Desmidiacez, Dr. 
Wallich considers that the twenty (and upwards) species be- 
longing to the genus Micrasterias “are reducible to less than 
half that number without infringing on a single reliable dis- 
tinction.”’ From this opinion I venture, indeed, to dissent. 
So far as I can see, I do not think it is possible to reduce 
their number in our books by more than oue or two. Paren- 
thetically, I may here, perhaps, just mention those cases. I 
allude to Micrasterias Crux-Melitensis (Ralfs), and MW. furcata 
(Ag.). The former only of these have I myself seen; but 
before I read Dr. Wallich’s statement of having met in India 
“every state intermediate” between these two, I was disposed 
to suspect their actual difference. Now, it is to be noted that 
Dr. Wallich does not in any other instance, while grouping 
together forms under a common specific designation, speak 
of “every state intermediate.’ The other instance may be 
M. truncata (Bréb.) and MZ. crenata (Bréb.). With these 
possible exceptions, I do not, at least at present, see the 
smallest reason to interfere with the established species in this 
genus. 
The consolidation and combining of well-marked species 
would appear to me quite as much to be deprecated on the 
one hand, as the wholesale making of species on accidental 
differences on the other. Far be it from me to aver that in 
this family all the individuals of any certain species seem to 
be, as it were, cast in the same mould. Even in the very form 
in question (J7. Americana) I have noticed sometimes one of the 
segments without the vertically set processes of the end lobe 
—in fact, like the figure in Ralfs.* The segment wanting 
these processes may have been the younger, and not fully 
grown; I have not seen a frond in which they were wholly 
absent on both segments. I have met J. denticulata with 
an almost entire semi-orbicular segment, something like that 
of Cosmarium Ralfsii, and again one segment somewhat like 
a nondescript Euastrum. Again, Docidium Ehrenbergii some- 
times presents a contracted inflated segment, somewhat like 
a nondescript truncate Cosmarium. I have seen a Kuastrum 
with one segment, as it were, double, giving the entire a some- 
what Y-shape ; and other examples might be cited. Can it be 
assumed that any such is hkely at the next repeated process 
* Op. cit., t..x, 1d. 
