COLLECTING FOEAMINIFERA 845 



larger proportion of foraminiferal shells than of the accompanying 

 particles ; so that, a large portion of the extraneous matter being thus 

 got rid of, the final selection becomes comparatively easy. Certain 

 forms of Foraminifera are found attached to shells, especially bivalves 

 (such as the Chamidw) with foliated surfaces ; and a careful exami- 

 nation of those of tropical seas, when brought home ' in the rough/ 

 is almost sure to yield most valuable results. The final selection of 

 specimens for mounting should always be made under some appropriate 

 form of single microscope, a fitie camel-hair pencil, with the point 

 wetted between the lips, being the instrument which may be most con- 

 veniently and safely employed, even for the most delicate specimens. 

 In mounting Foraminifera as microscopic objects the method to be 

 adopted must entirely depend upon whether they are to be viewed 

 by transmitted or by reflected light. In the former case they should 

 be mounted in Canada balsam, the various precautions to prevent 

 the retention of air-bubbles, which have been already described, being 

 carefully observed. In the latter no plan is so simple, easy, and 

 effectual as attaching them with a little gum to wooden slides. 

 They should be fixed in various positions, so as to present all 

 the different aspects of the shell, particular care being taken 

 that its mouth is clearly displayed ; and this may often be most 

 readily managed by attaching the specimen sideways to the wall of 

 the circular depression of the slide. Or the specimens may be 

 attached to discs fitted for being held in a disc-holder ; whilst for 

 the examination of specimens in every variety of position Mr. R. 

 Beck's disc-holder will be found extremely convenient. Where, as 

 will often happen, the several individuals differ considerably from 

 one another, special care should be taken to arrange them in series 

 illustrative of their range of variation and of the mutual connections 

 of even the most diverse forms. For the display of the internal 

 structure of Foraminifera it will often be necessary to make extremely 

 thin sections, in the manner already described ; and much time will 

 be saved by attaching a number of specimens to the glass slide at 

 once and by grinding them down together. For the preparation of 

 sections, however, of the extreme thinness that is often required, 

 those which have been thus reduced should be transferred to 

 separate slides and finished off each one by itself. 



For the collection and examination of fossil Foraminifera, which 

 are of great interest and importance, the following suggestions will 

 be of use ; they are the result of the ripe experience of Mr. F. 

 Chapman : 



Perhaps the foraminiferous clays are the most satisfactory for 

 those who desire to collect foraminifera. Ordinary clays require to 

 be slowly and thoroughly dried, broken into small pieces of about a 

 cubic inch or so, and placed in a vessel of water with steep sides. 

 After some little time the material will be found to have become 

 disintegrated. The vessel should then be shaken round, and after 

 the coarser particles have subsided the fine muddy portion may be 

 poured off. The materials should again be shaken with very little 

 water, and more water should then be added so as to cleanse the 

 mud, and the decanting process afterwards repeated. If this be done 



