Like what? As far as I know there is a sac stomach, a reproductive bundle of gonads and chamber for development of live young, a few lungs, a heart, and blood filtering skin.
-stomach: at least for the mobon descendants, I've assumed a U-shaped digestive tract
-reproduction: I've always drawn females with a dewlap-like womb sack, while males have a more compact sperm-producign organ (check my art, you'll see it. I'd suggest the dimorphic bandersnatch I made last gen)
-Lungs/heart: a little unsure aboot this, though I assume that these 2 things are connected. I tried speculating this in my "norat anatomy" thread
-Skin: what do you mean by "filtering"?