Dawsonoceras annulatum

I got permission to collect at local cemetery future expansion area where they dump piles of fill dirt. While there for about 30 minutes I found a Silurian period cephalopod called Dawsonoceras annulatum (sp?). The species may not be right but the books I looked at listed this as the species on specimens shown. The genus is correct though.

What I like about this cephalopod is that creature's shell is has lots of ridges making it easy to identify. Also it has sinusoidal grow lines that are neat. I think this only the third one I have found so far and maybe the second with the fossilized shell.

This specimen is about 6 cm long but has been dipped or was filled with concrete. Part of its shell is covered or has disintegrated leaving just a molded shape.