Autolytus charcoti (Ringed sylid worm)
In fact it has undergone a genus change and is now known as Epigamia charcoti (Gravier, 1906)
I can now be more precise: It is indeed a syllid, and its name is Autolytus charcoti (or, at least, that is the name John Day uses for it; it may have changed genus since them. John Day had only three records, so its quite a find!
Here's what George Branch says about your segmented worm
I am pretty confident it is a polychate and that it belongs to the family Syllidae
Any ideas on this beastie?
Can you help me to id this worm or put me on the right track to investigate further through your scientist friends.We only get as far as a segmented worm