CORALLINES. 233 



the sea-weed, spreading irregularly to the extent of several square 

 inches." 



Eschara foliacea (Frontispiece, No. 2). "This curious polypi- 

 dom," writes Dr. Johnston, " 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. The membrane is less than a line in 

 thickness, and consists of two layers of cells, separated behind from one 

 another by a thin plate down the middle. The cells open obliquely by 

 contracted roundish apertures disposed in a quincunx order on the sur- 

 face, and which, more especially when recently formed, are often covered 

 by a small operculum . When a portion of its skeleton is macerated in 

 diluted muriatic acid, it retains the original form, but becomes soft and 

 flaccid from the subtraction of the carbonate of lime. The cells are 

 liable to all the changes of form and character resulting from age in 

 general." 



The Corallines were at one time considered to be animals, and 

 polyp cells were described by Ellis and Lamarck as existing upon their 

 outer surface ; such, however, has been shown to be an erroneous de- 

 scription, and the calcareous material existing in the form of a coating 

 of variable thickness to a mass of cells evidently is of the vegetable 

 character. In the Nullapores all the intercellular spaces are filled with 

 lime, so that it would appear that the external surface of the cell- wall 

 possesses the power of separating lime from the sea-water, the crystals 

 of which take a certain definite form of arrangement. They are now 

 classed among plants, under the scientific terms of Lithophytes, or Stone 

 Plants, Corallines, and Nullapores. 



As we glance at the map of the world, and think of the profusion 

 of fragrant vegetation and delicious food almost spontaneously produced 

 on the lovely sunny islands of the broad Pacific, how startling does it 

 seem, when we reflect, that these islands, bearing on their bosoms gar- 

 dens of Eden, are entirely formed by the slow-growing corallines, 

 which, rising up in beautiful and delicate forms, displace the mighty 

 ocean, defy its gigantic strength, and display a shelly bosom to the ex- 

 panse of day ! The vegetation of the sea, cast on its surface, under- 

 goes a chemical change ; the deposit frc m rains aids in filling up the 

 little gaping catacomb, the fowls of the air and the ocean find a rest- 

 iug-place, and assist in clothing the rocks ; mosses carpet the surface, 



