FOSSIL INVERTEBRATES AND PLANTS 



103 



softer beds, conspicuously colored layers, or other permanent 

 natural features. 



When collecting loose fossils on a slope derived from two or 

 more soft, fossil-bearing layers, it may be necessary to dig away 

 some of the surface debris in order to locate and collect specimens 

 from the underlying beds that yielded them. 



Fig. 56. — A crinoid head. 



Fig. 57. — Segments of 

 crinoid stems. 



Collecting invertebrate fossils. — Fossils may occur embedded in 

 hard rock or loose on the surface. When they are found in a 

 hard matrix, it is necessary to break the rock to free the speci- 

 mens. For this purpose a hammer is necessary, preferably one 

 with a square face but, opposite to it, a chisel edge at right angles 

 to the shaft for splitting slaty rocks. In addition one or more 

 cold chisels or sharp points are desirable. A hand lens of 6 or 8 

 power is an indispensable item of equipment. Where the rock 



