i84 



The Naturalist. 



one of all the zoophytic, testaceous, or criistaceous reliqnias of this 

 limestone has ever been found in the upper coal series." It is a very 

 interesting fact, and worthy of special note, that the first appearance 

 of the shells, formerly called Unio, but now termed Anthracosia, in 

 the carboniferous rocks of this neighbourhood, occur in a thin layer 

 just under the soft bed coal. A few feet above that coal, there are 

 three separate beds which yield them in vast abundance. I have also 

 met with a very small univalve shell in the same beds, called Spirorbis 

 carbonaris, or little coiled shell of the coal-measures. Both these 

 shells occur in the middle coal-measures in prodigious numbers. 

 Once, while geologising at Low Moor, I found a little colony of the 

 beautiful Spirorhis, on the trunk of a large S'ujillaria, just brought up 

 to the surface, which were so perfect that at first I mistook them for 

 recent shells, and so lightly were they attached to the fossil plant that 

 they fell off while I was breaking it into a portable size. It is 

 interesting to note how a simple fact like this serves to illustrate the 

 condition of things in the old coal measure era, and how it proves that 

 the laws of Nature were then pretty much the same as now. The 

 Siffillaria, which was undoubtedly a land plant, appears to have been 

 uprooted or broken down by a storm or some other cause, and then to 

 have been carried into the estuary or lake, where the colony of shells 

 took possession of it. Then it became after a time water-logged, and 

 sank to the bottom, carrying its living freight with it, to become 

 entombed in their muddy graves. I need scarcely say that incidents 

 of this kind are of frequent occurrence in all our large rivers and 

 estuaries. 



There are many other interesting facts in connection with these 

 strata which time will not permit me to dwell upon at present, all of 

 which bear evidence of great changes in physical geography, having 

 occurred in the period represented by the strata about our hard and 

 soft bed coals. In concluding this part of my subject, I will briefly 

 summarise some of the changes in the level of the sea and land, 

 which the succession of these strata plainly teach us. First, we may 

 begin with the soft bed coal, which represents an ancient land surface 

 upon which the vegetation which formed that coal grew, then that 

 land slowly sunk below the level of a great estuary or lake, in which 

 vast numbers of fresh-water shells lived and died, generation after 

 generation, leaving their remains to form the "unio beds" ; then again 

 the land rose out of the water, and was covered by the plants which 

 formed the middle band coaL Again the land sank beneath the 



