8o8 NORTH AMERICAN INDEX FOSSILS. 



C. Laboratory Work. 

 I. Numbering and Labeling of Fossils. 

 The first thing on unpacking fossils is the proper numbering or 

 labehng of the specimens according to locaHty. A label to this 

 effect may be put in every tray of specimens, or better, each 

 specimen may be numbered by writing on it with india ink (color 

 selected according to color of rock), or a small disc of white or 

 colored paper may be glued to each specimen and the number writ- 

 ten on this. These discs may be purchased of any size, or can be 

 punched with a large punch from sheets of paper. The number 

 should correspond to one opposite the entry of locality and bed in 

 the " accession book." When extensive collections are brought in, 

 'especially from different localities, this labeling or numbering 

 should never be omitted. It is never safe to trust the memory, or 

 to trust to the keeping together of a large collection, where only 

 one tray is labeled. A small rectangle may be painted on the 

 specimen with white enamel paint, which dries rapidly, and upon 

 the hard surface of which a number can easily be written with 

 india ink and a fine pen. 



2. Cleaning Fossils. 



The removal of the matrix adhering to the fossil is a matter of 

 importance, for often significant parts of a fossil may be hidden. 

 Both mechanical and chemical methods are employed. 



(a) Mechanical Methods. — A number of coarse wire chisels, 

 well sharpened, a small hammer or mallet, and a sand-bag are the 

 first requisites. The sand-bag is a stout canvas bag about 8x 15 

 inches, filled about three fourths full of clean, moderately coarse, 

 angular sand, after which the mouth of the bag is closed tightly, 

 so that the sand cannot escape. This bag placed on the table, over 

 the leg, or better on an upright log or block standing on the floor, 

 serves as a support and buffer. The specimen may be placed upon 

 it in any position without fear of injuring the under side, or break- 

 ing it. The matrix can then be chiseled away carefully, heed being 

 taken that the matrix immediately adjoining the specimen does not 

 carry off fragments of the fossil. It is well to frequently moisten 

 the specimen with a wet sponge unless that should lead to separa- 



