205 
the plant is one of the commonest trees in the Savannahs, and one of 
the hardwood Acacias. It yields a fine bitter, and is used by the peo- 
ple as a substitute for Cinchona. It is employed in certain chronic 
inflammations of the throat, and is said to be superior to Peruvian bark 
in its medicinal effects. The wood is constantly used for fuel.— 
From Messrs. W. & G. Law, merchants, Edinburgh, specimens of 
raw cocoa, ground cocoa, roasted cocoa, rock Trinidad, or navy 
cocoa, cocoa-nibs, Fry’s chocolate, and a specimen of tea, known as 
Assam dust, which was stated to be scarcely known in commerce, and 
unnoticed by writers on teas. Messrs. Law remarked that it was a 
substance produced by friction during the process of preparing the 
tea. Leaves that are solid and heavy are the tenderest, and break the 
easiest; hence the quality of dust in Assam tea. This dust is too 
valuable to be thrown away, as it is often added to give strength to 
tea. — Other donations from Messrs. P. Lawson & Son, Mr. Andrew 
Murray, Mr. Robert Daw, Mr. G.S. Blackie, Professor Christison, 
Mr. George Waldie, Mr. W. H. Macfarlane, and Mr. Grant. 
North-Uist Moss. 
Dr. Greville mentioned that he had been in correspondence with 
Mr. Wilson upon the subject of the North-Uist moss, which had been 
referred by that gentleman to Leucodon Lagurus; while he himself 
had been disposed to consider it a variety of Hypnumcirrhosum. Mr. 
Wilson had, however, satisfied him that it could scarcely be so 
arranged. In the absence of fructification, Mr. Wilson preferred to 
regard it as a variety of Leucodon Lagurus (although there were cer- 
tainly some differences of character), rather than unnecessarily to 
multiply species. Dr. Greville was still disposed, on the strength of 
the great difference in habit, to doubt of its claim to the place assigned 
to it; and thought it probable that the fructification, when discovered, 
would remove it altogether from Leucodon. 
The following papers were read :— 
Structure of Diatomacee. 
‘On the Structure of Diatomacee ;’ by E. W. Dallas, Esq., F.L.S. 
The author directed attention to the list of Species which follows, 
and which, although imperfect, exhibits great variety in the forms, 
showing the Medway to be very fertile in these organisms :— 
