C R Y P T O G A M I A Alga.
G en. Char. Male, fcattered warts.
Female, fmooth fhields or tubercles in which the
feeds are imbedded.
Spec. Char. Cruft gray, cracked. Shields black,
flat, with an elevated, white, mealy margin,
when young drawn clofe over the centre.
F o R this new Lichen, found frequently on brick walls about
Yarmouth, we are likewife obliged to Mr. D. Turner. Its
cruft is not much unlike that of the preceding, but more ob-
folete, and not fo white. The fhields are fmall, very flat, not
at all immerfed, of a blueifh unpolifhed black. Their margin
is confiderably elevated, white, very mealy or downy. When
young it is clofely drawn or purfed up fo as to cover the black
part, in which ftate the ffuftification has the form of minute
white downy fpecks.
What purpofes thefe apparently inconfiderable produftioni
anfwer in the all-wife ceconomy of the creation we cannot
always determine; but we know enough to be certain that
each fpeeies is propagated and preferved by the fame laws as
the moft fplendid offspring of a tropical climate, and we may
be as certain that nothing is made in vain. Minute caterpillars
feed upon fome of thefe Lichens, as the Phalana Licbenella,
and probably more inconfpicuous ones which have not yet
been inveftigated. We know of one end which they all anfwer
in decay, the formation of vegetable mould, which being
waftied into the crevices of the ftones it is formed upon,
ferves to receive and nourifh the feeds of other vegetables.