P la t e CCL.
HILDENBEANDTIA RUBRA, Meni}.
Gen. Ch a e . Frond cartilagineo-membranaoeous, {not stony,) crustaceous,
suborbicular, adhering by its lower surface; composed of very slender,
closely packed, vertical filaments. Conceptades immersed in the
frond, orbicular, depressed, pierced by a hole and containing tetraspores
and paraphyses at the base of the cavity. H ildenbeandtia
{Nardo),— m honour o f ..............................?
H ildenbeandtia m ir a , Meneg.
H i l d e n b e a n d t i a rubra, Meneg. Mem. Biun. Nat. Padm. 1841, p. 10. Endl.
Zrd Suppl. p. 26. {excl. Syn. Berk.) Kiitz. Bkyc. Gen. p. 384. t. 78. f. V.
H i l d e n b e a n d t i a Nardi, Zanard. Alg. Adr. p. 135.
E h o d o d e r m i s Drummondii, Harv. in Ann. Nat. Hist. vol. xiv. p. 27. pi. 2.
H ab. On smooth stones and pebbles, between tide-marks, as well as in
deep water. At all seasons ? Common on the shores of the British
Islands.
G e o g e . D i s t e . Atlantic and Mediterranean shores of Europe.
D e s c e . Erond forming a thin, crustaceous expansion from half an inch to two
inches or more in diameter, at first orbicular, and spreading in concentrically
marked patches, but gradually sinuated and its surface irregularly corrugated
as it advances in age ; closely adhering by the whole of its under
sm-face to the rock or stone on which it grows. A small portion viewed
vertically with the microscope shows innumerable dot-Uke cells, imbedded
in a clear, firm, gelatine : and, thin slices, viewed laterally, prove the crust
to be formed of very densely' set, and closely cohering, slender filaments,
composed of minute ceUs. When in fruit the surface is pitted with disc-like
depressions, pierced in the centre by a hole which communicates with a
chamber or immersed conceptacle hollowed out of the frond, and containing
a few oblong, zoned tetraspores, among a number of paraphyses or abortive
filaments. The part of the frond forming the walls of the conceptacle is
of a much paler colour than the rest. Colour varies, according to locality,
from a clear blood-red to a dark red brown. Substance coriaceo-membra-
naceous, very firm.
Common all round the coast, on stones and rocks within
tide-marks, and also often dredged from deeper water. It forms
a thin skin-like film, so closely applied to the surface of the body
on which it grows that it is impossible to remove a specimen