COLLECTION, EXAMINATION, ETC. 299 



iiiferal sand often found useful to the manipulator is 

 that variously known to miners as ' vanning ' or 

 ' panning,' in which the sand is put into a shallow 

 dish or pan with water, and a circular motion or 

 dexterous twirl given to it, so as to throw over the 

 edge some of the lighter particles. By this plan, 

 conversely, our ' gold dust ' lies in the lighter portion, 

 and this must be collected in a larger vessel placed 

 under that in which the vanning is done. 



It occasionally happens that the dead shells of 

 Poraminifera are not so clean as they might be, on 

 account of dried sarcode or other extraneous matter 

 clinging to the surface ; or it may be necessary to 

 further empty the shells of the sarcode, shrivelled 

 though it may be, in order the better to observe their 

 internal construction. To clean the shells, therefore, 

 we may resort to the method of boiling the material 

 in a weak solution of caustic potash. After boiling, 

 the shells should be thoroughly washed in clean 

 water and dried slowly, as described before. The 

 foregoing processes apply both to recent and sub-fossil 

 gatherings, for the latter are often in as good a state 

 of preservation as the existing forms, as evidenced by 

 the faunas of estuarine deposits, fossil mud deposits, 

 and raised beaches. 



On the Extraction of Fossil Foraminifera from 

 Sedimentary JRocJis. — Fossil Foraminifera are obtained 

 from clays and marls by a process of disintegration, 

 the rock being washed down to a sandy and shelly 

 residue, and further cleaned by mechanical or 

 chemical means. In enumerating a few of the more 



