These pictures are of a Devonian Period clam called
Modiomorpha concentrica (Conrad, 1838). It was found in Clark County, Indiana USA in the Jeffersonville Limestone. A coral is growing on part of the shell that is probably an
Aulocystis.
This fossil belongs to my cousin who has been cleaning it.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghjUgw4sQ9xbBpdbwNm7FtiFt36ka9yNDVjR7e14fJwmXNA1F6kIBdqTrTZSce0a76bbsXlD7qLA-n3_do95OV_6MuehbD-CRN_61uJfgTh9f6poOb_UIxOT7R9mNUjMVMjH_CYHAYVSBP/s400/modiomorpha-with-aulocystis-coral5.jpg)
I used 1889
A Monograph of the Fossil Shells of the Silurian and Devonian Rocks of Kentucky by Henry Nettelroth (1835-1887) found
here. This first image is from Plate II figure 10.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiH3jd7rvWIYHMHsaB8zGd5XlN3DJNexPnAT7KN6eg9qUQtvXAxmeV7gKb_-vIm7Fu2wZLcapwBdW3j4IHC56G3id0sBnZHFa2wxNk9QtgqZ2j6aUvL0RzdfE4qhESxwkQ268lvL3SnyA8-/s400/nettleroth-image-plate-II-figure-10.jpg)
The last image is from Plate II, figure 11.