402 THE MICROSCOPE. 



of the deep, found usually on old shells, an inch in height, 

 spreading itself fan-like, and of an ashy colour, deeply 

 divided in a dichotomous manner into narrow, thin, plane 

 segments, truncate at the end, formed of four or five series 

 of oblong cells, capped with a hollow globose, pearly, oper- 

 culum seated between the spines, of which there is one on 

 either side of the circular aperture. The opercula are so 

 numerous, that they give to the upper surface the appear- 

 ance of being thickly strewn with orient pearls; the under 

 surface is even and longitudinally striated, the number of 

 striae corresponding to the number of rows in which the 

 cells are disposed. Dr. Johnston describes, amongst many 

 other British species, F. membranacea, " a gauze-like incrus- 

 tation on the frond of the sea-weed, spreading irregularly 

 to the extent of several square inches." 



Eschara foliacea. This curious polypidom attains a 

 large size, being often three or four inches high, and 

 from twelve to twenty inches in diameter. It may be 

 described as a broad membrane, twisted into winding- 

 folds, leaving large sinuosities and cavernous interstices ; 

 it is very light, and floats in water; crisp when dry, 

 membrano-calcareous, cellular, of a yellowish-brown colour, 

 roughish, and punctured with the numerous pores which 

 open on both sides. When a portion of the skeleton 

 is macerated in diluted muriatic acid, it retains the 

 original form, but becomes soft and flaccid from the sub- 

 traction of the carbonate of lime. The cells are liable to 

 all the changes of form and character resulting from age 

 and death. 



The species best known in its skeleton form is Coral- 

 lium rubrum, " Red coral ; " the coral of commerce, and 

 an inhabitant of the Mediterranean and adjacent seas. 

 In appearance it resembles a tree devoid of leaves and 

 small branches. It requires about ten years to arrive at 

 maturity, and is then about a foot in height. Its skeleton 

 or axis is the polished brilliant red-stone used in orna- 

 mentations; being solid, channelled, ramified, and fixed 

 by a broad base, with a thin external, fleshy covering, of a 

 pale blue colour, and studded over with star-like polypes, 

 which extend their feelers to grasp at prey. When brought 

 into the air, the pulpy body of the animal soon decays, 



