M a t/ C U V /.
Ri'fii;
I'i, ft'
hliil ^
ill 8
Reeve B e iiliam & H<'e\e, i
Ser. RH0D0SPBEMEA5. Tam. Corallinem ?
P l a t e CLXVI.
LITHOCYSTIS ALLMANNI, Haro.
G e n . C h a r . “ P la n t calcareous, consisting of a single .plane of c eM e s ,
wliich a re disposed in ra d ia tin g dichotomous series fo rm in g an a p pressed
flabeUiform fro n d .” AUm. L i t h o c t s t i s {A llm ),— hwa.
XiOos, a stone, an d Kva-ns, a bladder; because th e ceUs are coated w ith
a stony membrane.
L i th o o y s t i s AMmanni.
H ab. Parasitical on Ch „
Dublin Bay, Professor
G e o g r . D i s t r .
%a clavellosa, from an Oyster-bed, Malahide,
D esc r. “ This minute Alga presents itself to the naked eye in the form of very
smaU whitish dots scattered over the surface of the vegetable, which it has
selected for its parasitic growth. Under the microscope each dot is seen to
consist sometimes of one, but more frequently of a cluster of several
transparent and colourless flabelliform fronds, whose component cellules
radiate from the apex of the frond, and after repeated dichotomous division,
terminate by forming a convex margin. In abnost all the ceUs there may
be seen a very evident sphaerical nucleus. The whole plant is brittle, and
pnlverisable underpressure, its hyaline frond being mainly composed ot
carbonate of lime, which does not merely incrust it, but is mtimately
incorporated with its tissues. In Utliocystis, indeed, the carbonate of lime
would seem in every way to represent and replace the sdica oi the Biato-
■macem. Under the action of dflute acid the mineral matter is entirely
dissolved, and nothing remains but an exceedingly delicate orgamo him, m
which the original form of the plant can with difficulty be detected. Nothing
distinctly referable to fi-uctification has been seen m any of the specimens
examined. Uthoeystis manifestly approximates very closely to CoUochatf
a genus established by Brehisson for a fresh-water Alga, and one with
which the Blylactidmm of Kiitzing is evidently identical. Setting aside
the sheathed bristles of CoUochcete— a character by no means constant—
XiaoCT/ii« would appear to differ from the latter chiefly by its calcareous
composition, a feature, however, of much importance, and bringing
the present plant into direct relation with the Corallines. A lh i.
In'one of the'hest books of the last generation written for the
amusement and instruction of young persons,—I mean Evenings
at Home,—time, is an excellent paper, headed “ Eyes and no
Eyes, or*the Art of Seeing.” The history of the discovery of the
curious and beautiful little plant here figured reminds me of that
paper, offering, as it does, a striking illustration of the advantage
to a naturalist of having his eye constantly on the watch. My