Can anyone identify these Portland stone fossils?

[Stephen Rowley <srowley@xxxxxxxxxxxxxx>]

These fossils are the internal casts from a gastropod
(snail to you and me) called Cerithium portlandicum  or
Aptyxiella portlandica.  Same fossil just different
naming systems.  They are very common in the 'Roach'.
This is an inferior stone found below the 'Freestone'

Although it is hard and can be used for building, the
fossils are considered to be flaws and reduce its value.

You will also find the internal casts of Trigonia
gibbosa in the Roach. The delicate features of this have
given rise to the name 'Horses heads or 'Portland
devils'.

There are several books which describe the geological
aspects of Portland Stone, my favourite is 'The Dorset
Coast' by GM Davies, but it is well out of print so
you'll need to find a second hand copy.

The museum on Portland is worth a visit, you will find
more information about the fossils there.

There is also a big church made entirely of Roach.

Keep banging those rocks together guys.

Steve

(was a geologist, now a sculptor)