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



Speaking generally, it can be traced with, the greatest ease 

 over the whole of the Lower Coal Measure area in Lanca- 

 shire and onwards into Yorkshire, where, as the Halifax 

 Hard Bed, it is as readily recognisable as elsewhere. 



Wherever it occurs it seems to yield the " bawm-pots " 

 with their loads of animal remains, and the even more cele- 

 brated " bullion-balls," always rich in well preserved plant 

 tissues. 



In point of time the bullion balls are slightly, but not 

 much, older than the "bawm-pots." 



The great wealth of the shales above the Mountain Four 

 Feet and Bullion seams lies in the lowest portion, and ranges 

 as high as the " Soapstone Bed " of Trawden and Colne, 

 which occurs about four to seven feet above the coal. 



Higher than this there is a marked falling off in numbers 

 and species. 



From above the Fireclay coal no species have been recorded, 

 largely, no doubt, owing to the fact that it is never worked 

 and is difl&cult to find on exposures. 



The shales over the Upper Mountain Mine show that the 

 falling off in species noticed in the upper shales over the 

 Mountain Four Feet and Bullion mines had continued. 

 Thirteen species are known, only two of Avhich are cephalo- 

 poda, seven being pelec}^poda, and four fishes. The marked 

 falling off of cephalopoda and fishes is evidently an indica- 

 tion of a return to more unfavourable and less marine 

 conditions. 



The thin coals and shales above the Upper Mountain 

 Mine are very little known and have never been worked out. 

 But two species of mollusca are known from them. 



One feature which will probably strike the student is that 

 animal life was more abundant immediately after the 

 deposition of the thickest coals, and more scanty over the 

 thin seams. 



