My guess is that it is a female and she has just laid a heap of eggs in that web sack. Her body (and I have just learned that it is called a opisthosoma) was much smaller here than than in the earlier shot.
Calling any Arachnologists (well there seems to be at least one of just about every other profession on 365) is this correct?.
Oh my Poppo, I'm with Rhoda on this one, the mystery spider would have to go (especially if there's going to be babies) not squished of course, just thrown over into next doors yard
Now aren't you glad that you prevailed over Rhoda? Imagine going to the prenatal facility only to find that Godzilla had crushed it. I want to see the babies.