350 PAL/EONTOLOGY 



little at a time on black paper, examined with a lens and 

 fossils picked out with a moistened sable brush, or in the 

 case of heavy ones with a fine forceps. Siftings of friable 

 rocks are picked over in the same way. 



Chalk may be scrubbed under water with a stiff brush, 

 and a concentrate obtained by the method just described: 

 the chalk from the interior of large fossils (such as 

 echinoids) is often the most fruitful, because the small 

 shells have been more protected from destructive move- 

 ments in the ooze on the sea-bottom. 



The methods of removing of matrix from a fossil 

 depend greatly on their respective toughness. When 

 the fossils are strong and the matrix friable, washing 

 with or without the help of a brush (a tooth-brush is very 

 convenient) may be enough ; but some fossils (many 

 lamellibranchs) will break into pieces if wetted, and must 

 be cleaned dry with the help of some tool. A shoe- 

 maker's awl mounted in a handle is very useful for 

 tough matrix ; in other cases a mounted needle, pin, or 

 steel pen, or even a common pocket-knife may be service- 

 able. The golden rule about all such tools is that they 

 should never be used to scrape the matrix away from the 

 fossil (with a possible exception for silicified and pyritized 

 fossils, where the fossil is harder than the steel of the 

 tool). The aim should always be to put such a strain on 

 the matrix by means of a tool, that it breaks away from 

 the fossil without the tool touching the latter. The 

 application of this rule to particular cases must be very 

 varied. 



As an example, take the case of a graptolite, part of 

 which is exposed on the lamination surface of a shale, 

 partly buried under other laminae. The natural first 

 idea is to push a knife-blade between the laminae and 

 separate them, but the probable result of this will be that 

 the_ laminae break away anywhere except where the 



