Collecting and Preparing Foraminifera 215 



120 meshes to the inch respectively will be sufficient. 

 The writer's sieves are of copper, 4 inches high, 4 inches 

 diameter at top, sloping to 3 inches diameter at the bottom. 

 A smaller size, made of telescope-tubing IJ inches in 

 diameter and 1 inch deep, is very useful for washing small 

 gatherings. Zinc, which is cheaper than copper, can be 

 used for the sieves. 



The wire gauze, which can be obtained from any large 

 ironmonger, varies in price according to the number of 

 meshes to the inch, ranging from a few pence per square 

 foot to four shillings for the finest obtainable, which has 

 120 meshes to the inch, the diameter of each aperture 

 being about -^^o inch. If a finer sieve than this is required, 

 as it sometimes may be, the size of the aperture may be 

 reduced by silver-plating the gauze, or, preferably, by the 

 use of silk bolting cloth, which may be obtained up to 

 200 meshes to the inch. The wire gauze must be strained 

 tightly over the sieve and soldered neatly to the edge, so 

 that there is no ledge of solder inside to retain unwashed 

 material. If silk is used, a sieve must be made without a 

 bottom, and having a turned-back edge at the lower end, 

 so that the silk may be strained across and secured with 

 string or a rubber band. The most useful sizes for a series 

 of sieves are, in my opinion, 12, 20, 40, 80, 120 and 150 

 (silk) meshes to the inch. 



Before cleaning the material it must be slowly and 

 thoroughly dried. It should then be passed through the 

 twelve-mesh sieve to remove all the coarse debris, stones, 

 shells, cinders, etc. None of the British shore species, ex- 

 cept parasitic forms, will be found in this coarse residuum, 

 but it should be looked over with a pocket lens for these or 

 for abnormally large specimens. In some dredged materials 

 and in tropical gatherings, however, this coarse residuum 

 will be found to be full of foraminifera. 



The material which has passed through the twelve-mesh 

 sieve consists of foraminifera mixed with other light debris 

 and a considerable quantity of sand, and the collector 



