55 



Chert from Portlandian beds, showing the same structure as flint. 



Sand collected from a road repaired with flint. Consists principally of flint. 



Sand, Blackfoot loam, from Charlton, Kent. Principally quartz, with about 

 1 per cent, of flint. 



Thanet sand from Reculvers. Principally quartz ; about 1 per c(mt. of flint. 



Chalcedony from Iceland, showing it to be crystalline silica, bearing the same 

 relation to quartz crystal and massive quartz that fibrous gypsum does to selenite 

 and common gypsum. 



Chalcedony from Iceland. 



Chalcedonic pseudomorph, showing rotary polarization, by W. Hawkins 

 Johnson. 



Present 59 members. 



April 26th, 1872.— Chairman, Dr. R. Braithwaite, F.L.S., 

 Vice-President. 



The following donations to the Club were announced : — 



" Science Gossip " from the Publisher. 



*' The Monthly MicroscopicalJournal " ... ,, 



** The Popular Science Review" j? 



" The Proceedings of the British Naturalists' ") ^.^^ Society 



Society" ... ... ^ 



"The first Report of the South London Mi-) , ^, , 



croscopical and Natural History Club " ^ 

 " The Journal of the London Institution " ... the Librarian. 



One Slide Mr. T. Rogers. 



The thanks of the Club were voted to the donors. 



The following gentlemen were balloted for and duly elected members of the 

 Club:— Mr. Herbert Curwen, Dr. R. E. Dudgeon, Mr. J. W. Goodinge, Rev. 

 William Law, Mr. S. H. Roberts, and Mr. Edward Tozer. 



Mr. J. G. Waller read a paper, entitled ' ' Observations on Fresh Water 

 Sponges," illustrating the subject by diagrams. 



The Chairman proposed a vote of thanks to Mr, Waller for his interesting 

 paper, and invited observations from gentlemen present. 

 The vote of thanks Was carried unanimously. 



Mr. Charles Stewart said that he feared he had lost a great deal of Mr. 

 Waller's paper owing to the acoustic properties of the room, but he understood 

 him to lay considerable stress upon the external forms of these sponges as a 

 means of identification. He was himself more acquainted with the salt water 

 sponges, and what he knew of these would lead him to judge that mere external 

 form would be itself only a very rough and uncertain method upon which to form 

 a decision. He should also rather fancy that the process which Mr. Waller had 

 described, together with the flaccid condition, was perhaps due to to the condi- 

 tion of the water in which the sponge was, so to speak, endeavouring to grow, 

 although it could hardly succeed in managing it. 



Mr. Holmes inquired whether Mr. Waller had observed any cilia on those little 

 bodies which he had mentioned ? 



