44 
e 
interrupting and imposing the distinction and separation 
of the rocky matter sufficient to keep its form visible. 
The other four figures are from the same specimen as 
Martin figured: I cut a piece from it in search of the 
spiral cartilage, but it was obliterated : we may still hope 
to see it in perfection in some other. The Irish and Der- 
byshire specimens are in a much lighter coloured stone 
than the others. 
