We’ve been spending the morning boning up on the primary candidates for Philadelphia District Attorney, and boy, are our arms tired. Let’s review, shall we? There’s noted tragedy-monger Brian Grady, with whom you may already be familiar. And then there’s Dan McCaffery — the brother of noted “Eagles Judge” Seamus McCaffery — who just took a major swipe at candidate Seth Williams over alleged failures to disclose income, a move designed to attempt to knock Williams out of the race. Seth Williams, for his part, seems to have progressive support, but it remains to be seen whether he deserves it or not, especially as one particularly stinky campaign contribution seems to be giving his rivals lots of post-Fumo ammo. Williams, in turn, is calling into question signatures on the petitions to run for both McCaffery and Michael Turner, who’s already been tagged as the “Nutter” of this race, but has already had at least one major media flub. Who’s left? Dan McElhatton, an attorney in private practice with close ties to the Nutter Admin who would seem to have stayed out of the fray thus far, and sacrificial lamb Michael Untermeyer, the sole Republican in the whole race. PhillyMag recently ran an overview here — which City Paper called “cynical,” only showing that they ain’t seen nothing yet — and you can get all the mugshots and stats at Committee of Seventy. Strap yourselves in, gang: It’s gonna get ugly, and boring.