This little nasty is about 2" long.
I probably need to give it an ink wash to bring out more details, but I was going for a subtle, bleached out specimen look. I don't think subtle works at this scale.
I've also come to the sad realization that I need to get a new camera. Out of over a dozen shots this was the only one that was even close to being in focus.
Update: A kind emailer pointed out that this little critter bears an uncanny resemblance to a prop parasitic worm that appeared in the "Cthulhu Live: Delta Green" supplement. I think the worm in the book is a project I did back around 2000 and posted to the Cthulhu Live mailing list. If anyone has access to that book I'd appreciate it if you could drop me a line, since I've never actually seen it.