380 MR. H. BOLTON, F.B.S.E., ON [Feb., 1904. 



great measure to the fact that fossils are more readily 

 obtainable from the roadways and roofs of the seams 

 than from surface exposures, where they readily crumble 

 awa3^ 



Surface exposures are fairly plentiful in doughs and 

 stream courses, but unfortunately both shales and fossils 

 readily disintegrate when thus exposed, and little can be 

 made of the latter. 



Even if got out whole, the specimens are apt to fall in 

 pieces on drying, unless they have been extracted from 

 ironstone nodules or ironstone bands which occur in the 

 shale. 



The presence of iron pyrites is also a fertile cause of 

 destruction. 



The roof shales of the Upper Foot or Bullion seam 

 contain great numbers of flattened spheroidal masses of 

 earthy carbonate of lime with an outer crust of iron sulphide 

 or pyrites, usually in a very stable condition. These 

 **bawm-pots," as they were once called by the colliers, are 

 richly fossiliferous, and must not be confounded with the 

 more irregular masses known as "bullion balls,'' which occur 

 in the coal itself, and consist of carbonised and well preserved 

 plant tissues. 



In the accompanying pages all the animal fossils of the 

 Lancashire Lower Coal Measures, other than the gasteropoda 

 and cephalopoda, are fairly completely recorded — so far as 

 they are known up to the present time. 



The gasteropod and cephalopod groups have been 

 partially omitted, because the former is in great confusion 

 — few definite species being recognised and several 

 xmdescribed — the latter (cephalopod) group, including a 

 number of species of Orthoceras, to which the same remark 

 will apply. 



