Collecting and Preparing Foraminifera 213 



gathering. The best scraper is a thin plate of celloidin, 

 such as a * Photographic ' film, as the thinness and flexi- 

 bility of this material enables the collector to make his 

 scraping with less admixture of sand than is possible with 

 the glass or metal slip usually recommended for use. 



Thus equipped, the collector sallies forth between the 

 tides. Probably everyone has noticed when at the seaside 

 the white lines which run along the sands parallel with 

 the retreating tide. A pocket lens shows that the white 

 material consists of the minute shells of foraminifera, of 

 which some are of a lustrous white colour, due to the 

 comparative abundance of the Miliolidce a family of 

 common occurrence in shore-gatherings, characterized by 

 opaque shells of a milky white or ' porcellanous ' texture 

 while others are more or less glassy and transparent. 

 These 'hyaline' forms are much less noticeable to the 

 naked eye. They are mixed in varying proportions with 

 fragments of shell substance ostracode shells, cinders, 

 and the lighter debris of the shore and their presence in 

 these lines is due to the separating action of the water, 

 which on a smaller scale we shall later on employ in the 

 cleaning of our collected material. The rocking action of 

 the wave on the extreme edge of the ebbing tide keeps 

 these shells and fragments of light specific gravity in 

 suspension until after the heavier sand-grains have sub- 

 sided, and so they are left behind in the ripple marks and 

 depressions of the sand. Sometimes a local eddy of the 

 tide, produced by the neighbourhood of a projecting rock, 

 or of groins and piers, causes the material to be gathered 

 together in large quantities, which show as extensive white 

 patches on the sand, and prove a real gold mine to the 

 collector, who will then obtain more material in half an 

 hour than he could gather in several days from the ripple 

 marks. 



The collector must not conclude that there are no fora- 

 minifera present because there are no white patches to be 

 seen, but, remembering the way in which these patches are 



