86 



M. Damour on the Composition of Nullipores. 



of coralloid branches, cauliflowers, lichen, &c. They possess nearly 

 the colour, hardness, and tenacity of calcareous matter. They are 

 easily pulverised. When immersed in a weak acid, all the earthy 

 matter which they contain dissolves with effervescence ; there re- 

 mains a skeleton of organic vegetable matter, retaining precisely the 

 form of the original specimen, and presenting the cellular tissue 

 peculiar to the marine algse. This organic matter exhales the 

 peculiar alliaceous odour which characterises marine vegetables. It 

 is spongy and nearly transparent, and is reduced to a very small 

 bulk by drying. Treated with solution of potash or soda, it doe:i 

 not dissolve either cold or hot, but it becomes more transparent, and 

 thus behaves like most vegetable tissues. It burns with flame, and 

 usually leaves very little ash. 



The author states his obligation to MM. Deshayes and Michelin 

 for the first specimens which served for this examination. Lately 

 M. Decaisne supplied him with more, from the collection of the 

 Museum of Natural History, belonging to the well-known species. 



The following table exhibits the results of the analyses of various 

 species : — 



Carbonate of lime. 



Carbonate of magnesia 



Soda 



Potash 



Peroxide of iron 



Sulphuric acid 



Phosphoric acid 



Chlorine 



Sulphate of lime 



Organic matter 



Moisture 



Silica 



Millepora 



cervicornis 



from 



Brehat. 



(Manche.) 



Mixed silicious sand — 



87-32 

 8-51 

 0-45 

 0-34 

 0-66 



0-89 



0-23 



undeter- 

 mined 



0-35 

 0-64 



0-63 



99-91 



Litho- 

 phyllum 

 (Mediter- 

 ranean.) 



77-36 



11-32 



0-55 



0-27 



0-08 



0-95 



0-32 



^ 0-60 



4-70 

 1-46 



1-36 



98-97 



3. 



Melobesia, 



new 



species? 



(Algeria.) 



72-78 



12-32 



1-75 



0-65 



0-20 



1-25 

 0-38 

 0-34 



3-95 



1-40 



4-'28 



99-30 



Amphiroa 



tribtUus 



(Antilles.) 



70-83 



16-99 



089 



0-39 



0-93 

 0-27 



0-53 



0-20 

 6-40 

 1-38 



98-81 



Halymeda 



opuntia 

 (Red Sea.) 



86-17 

 0.56 

 1-13 

 0-54 



undeter- 

 mined. 



undeter- 

 mined. 



0-84 



0-55 

 8-30 

 0-90 



98-99 



Galaxaura 



frag'dis 

 (Antilles.) 



72-56 

 0-86 

 0-73 

 102 



undeter- 

 mined. 



undeter- 

 mined. 



1-17 



1-80 



17-50 



0-95 



2-20 



98-79 



The number 1, obtained on the coast of Brehat (Manche), forms 

 considerable ridges, which are worked for obtaining hydraulic lime. 

 The specimen employed for analysis was slightly disintegrated on the 

 surface, and, as it were, fossilised. It is to this circumstance that the 

 author attributes its containing so little organic matter. No. 3 was 

 obtained by M. Deshayes on the coast of Algeria. This species is 

 developed in great abundance on a vast extent of this coast, and pre- 



