COLLECTION AND PRESERVATION OF FOSSILS 349 



Care must be taken to pack up specimens so that they 

 do not get broken in transit home : heavy fossils must 

 not be placed on top of fragile small ones, for instance. 

 They must be so labelled that there will be no mistake as 

 to the exposure and the particular bed from which they 

 came. At the time it may seem quite safe to trust to 

 memory, but a week afterwards an unlabelled specimen 

 will prove a serious worry to the conscientious collector. 



The extracting and cleaning of fossils the removal of 

 fossil from matrix or matrix from fossil is an art in 

 itself. In extracting large specimens from hard rocks, 

 such as tough limestones, the latter must be subjected to 

 great stress the blow of a sledge-hammer may make a 

 fossil jump out quite clean. A screw-movement stone- 

 breaking machine may be effectively used in the same 

 way. At other times when the fossils are fragile and 

 firmly cemented to the matrix, their violent extraction 

 may be almost hopeless, but heating the rock and cooling 

 it by plunging it into cold water may have the required 

 effect. In the extraction of small fossils, such as fora- 

 minifera and ostracods, from sands and friable rocks, the 

 rock is first broken up and then passed through a series of 

 sieves : the great majority of fossils will be found between 

 a mesh of 32 to the inch and one of 64 to the inch. In 

 the case of stiff clays, another method must be used : 

 the clays are broken up into small pieces, about the size 

 of a pea or larger, and heated on a metal plate over a 

 flame until thoroughly dry, when they are dropped while 

 still hot into cold water in a circular dish. The clay 

 quickly disintegrates into mud, and by keeping up a 

 swirling of the water by constant movement of the dish, 

 decanting the muddy water and adding fresh over and 

 over again, all the argillaceous material is at length 

 removed and a concentrate left, consisting of sand-grains 

 and small fossils. This is dried and then spread out, a 



