Fig. 160. MELOBESIA LICHENOIDES. 
Colour. Pale-lilac, or rather mauve. 
Substance. Hard ; stony ; solid ; but thin and extremely brittle. 
Character of Frond. A lichen-like expansion, composed of thin, circular, leafy plates, one 
above another ; attached to rocks by a central base. The foliations generally free at 
the margins ; often overlapping each other {imbricated). 
Measurement. From 1 to 5 inches across. 
Fructification. Only one kind known. Clustered strings of spores in large, conical, prominent 
capsules ; sessile on the frond. 
Habitat. Cornwall and west of Ireland. On rocks and in tide-pools near low- water. Not 
uncommon. 
Fig. 161. HILDENBRANTIA RUBRA. 
Colour. Bright, or sometimes dull red. 
Substance. Gristly-membranaceous. 
Character of Frond. A thin, skin-like film, forming a circular or irregular red patch; 
adhering by its under surface to the rock. 
Measurement. Indefinite. From 1 to 6 inches, or thereabouts, in extent. 
Fructification. Only one kind known. Tetraspores in round cavities, sunk in the frond. 
Habitat. Our coasts generally. On smooth stones and pebbles between tide-marks. Common. 
So thin that it looks merely like a red stain on the stone. When in fruit its surface is 
pitted with small disc-like depressions, underneath which lie the spore-cavities (conceptacles). 
The figure of the cavities gives more the appearance of raised capsules ; but concavities are 
difficult to represent. 
Fig. 162. HAPALIDIUM PHYLLACTIDIUM. 
Colour. White. 
Substance. Thin ; limy ; brittle. 
Character of Frond. Minute dot-like patches, which, under the microscope, prove to be 
composed of one or several thin fan-shaped, watery fronds. 
Measurement. The dots from to ^ of an inch across. 
Fructification. Unknown. 
Habitat. Malahide, Dublin, and elsewhere. Parasitic on Chrysymenia clavellosa and other 
small alg£e. 
A verj'' remarkable little plant, and said to he common ; hut, if so, it wants looking for. It 
was, until lately, known as Lithocystis Allmanni. (See Haiwey’s Manual of Br. Mar. Algce, 
2d edition, p. Ill : 1849.) It is now (1862), by many, believed to he the young of a Melohesia. 
70 
