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CHLOROCOCCUM M u r o r um .
Wall Cklorococcum.
C la s s a n d O r d e r CRYPTOGAMIA ALG®, L m « .— N a t . O r d . ALGjS, Just.
GEN ERIC CHARACTER.
Granula omnino libera, winima, aggegata, absque gelahna.
Granules quite free, minute, aggregate, unaccompanied by a gelatine.
S P E C IF IC c h a r a c t e r .
C h l o b o c o c c u m Murorum; Granulis viridis, simplicibus, minutissimis, osali-
oblongis.
C. granules green, simple, very minute, oval-oblong.
P b o t o c o c c u s viridis, Ag. Syst. Alg. p. 13.
H ab. On walls and stones, frequent.
Plant producing spots on walls and stones, of a yellowish-green colour,
and at first very small, b u t afterwards indefinitely larger, from a number
becoming confluent. Granules exceedingly minute and numerous,
varying in form from nearly globose to oblong, pellucid, green, totally
unmixed with any gelatinous matter.
This minute species was first discovered in this country hy
the Rev. J. M. B e r k e l e y , on the freestone walls of Christ
College, Cambridge. It is, however, one of those plants, which,
after having been once detected hy an acute observer, is found
to be very common. It may he easily passed over for the crust
of a lichen in a young state; and I would not take upon me
to say that such is not actually the fact. A specimen I communicated
to my friend Professor A g a r d h , has been hy him
identified with his Protococcus viridis. In my observations
upon the Bed Snow (t. 231.), I have limited the genus Protococcus
to the alga colouring the snow, and therefore place the
present plant in the genus Chlorococcum, defined at t. 262.
Such, however, being the generic name, I have been obliged to
change the specific one of viridis which had been bestowed by
325
VOL. VI.
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