420 
The Hon. Mr. Strangways on the 
circumference. These have been supposed to be heads of alcyonites, 
analogous to those of the green sand of the Isle of Wight, and to 
be connected in origin with some obscure traces of stalks which 
the limestone sometimes presents on its weathered surfaces. But 
these stalks having never yet been found together with the balls, 
this is still only a conjecture. They may perhaps be only concretions 
of calcareous spar, similar to those contained in the black clay 
below, but in which the bitumen is wanting. They are found 
commonly in all parts of the limestone district. 
Another variety of these argillaceous beds, which appears to be 
confined to the eastern borders of the limestone, is that which is 
thickly sown with brown grains of clayey iron ore, as some other 
beds are with green earth.* These grains have a slight resemblance 
to those in the red or upper beds of the inferior oolite of the south 
coast of England, and which also occur in France, but are not so 
black. I have not been lucky enough to find this variety in situ , 
but fresh fragments of it are not uncommon in the Popovca, 
Coshelevca, and other brooks. 
Perhaps the most singular appearance which this limestone 
presents, is that so common on the Pulcovca and other places, 
where a yellow bed is, as it were, blotted with various colours, and 
where sometimes beds, coloured differently, alternate ; as is the case 
on that stream with the red and yellow magnesian, and greenish 
varieties. f The contiguous surfaces of these beds are very rugged, 
* Perhaps they are the same substance with the iron which it contains, in a different 
state of oxydation. 
+ The limestone as well as all the beds of the whole formation including the blue clay, 
have a tendency to a cubic fracture. The upper surfaces of they limestone beds are often 
crossed by two sets of parallel fissures dividing it into square pieces easily separable. 
Where the highly coloured beds abound, as on the Pulcovca, the quantities of red, green, 
yellow', and grey cubic fragments, which are often mixed together, resemble the tessera of 
a Roman tessellated pavement. 
