By the way the intergular scute is enveloped by the gulars, it looks like a Chelodina species, but the neck looks pretty short. Are they from the Sydney area? John Cann's book(Australian Freshwater Turtles) is excellent, but it makes it sound like there are many locallity-specific "morphs" found there. From what I hear, he's a really nice guy, maybe you could try and get a hold of him? I'd guess C. longicollis.
:My friend in Sydney has a small group of these in his yard. This was one of the smallest ones. I don't know how to post multiple pics in one post, so I will have to do it one at a time.