438 Mr. H. J. Carter on Specimens 



nearly all the marine organisms that exist in the Indian 

 Ocean. 



The " specimens " consist of calcareous nodules of different 

 sizes, which may be said to originate, in the first place, in 

 the agglutination of a little sea-bottom by some organism into 

 a transportable mass, which, increasing after the same manner 

 as it is currented about, may finally attain almost unlimited 

 dimensions. They are therefore compounded of all sorts of 

 invertebrate animals, whose embryos, swimming about in every 

 direction, find them, although still free and detached, of suffi- 

 cient weight and solidity to offer a convenient position for 

 development 5 and hence the number of species in and about 

 them. 



They vary in form and weight in proportion to the amount 

 of loose or solid material in them, some being round, hollow r 

 clathrous, others more solid, but much creviced, and some 

 almost entirely solid 5 while they may be more or less rugged 

 on the surface from the nature of the organisms of which they 

 are chiefly composed, whether through development in situ 

 or subsequent agglutination. Perhaps no family of organisms 

 has entered into their composition or increased their solidity 

 more than the calcareous Algas (Melobesiw), which, in succes- 

 sively laminated or nulliporoid growths, has rendered these 

 nodules almost solid throughout or covered with short, thick,, 

 nulliporiform processes. I am not sufficiently acquainted with 

 the calcareous Alga? to say what the species are ; but the 

 common incrusting one hardly differs from our Melobesia 

 polymorpha ; and this seems also to have produced the nulli- 

 poroid growths to which I have alluded. There is also 

 another laminar species with larger cells which are quadran- 

 gular ; but this does not appear to be so common, while 

 the loose, deciduous, flat, reniform articulations of Flabellaria 

 opuntia are agglomerated with every thing, showing that this 

 calcareous alga or coralline, which is very common in the 

 tropics generally, is not less so in the Gulf of Manaar. 



As it is upon these agglutinated compounds, as well as in 

 their crevices and the excavated cavities formed by lithodo- 

 mous sponges in them, that the organisms to be hereafter 

 mentioned have been developed, I shall henceforth allude to 

 the former under the term of " Melobesian nodules." 



Next to the part which the Melobesice have taken in their 

 formation may be mentioned the sessile Foraminifera ; and 

 these have, in their turn, been overgrown, in many instances, 

 by Polyzoa, which, too, is a class of which I know so little 

 that I am not able to point out the different species present ; 



