Mitochondrial genome rearrangements in bivalves and representatives from other molluscan classes. All genes are transcribed from left-to-right except those indicated by underlining, which are transcribed from right to left. The bars show identical gene blocks. The arrows indicate gene translocation and the circling arrows indicate gene inversion. The grey blank boxes represent the uncompleted sequences. The non-coding regions are not presented and gene segments are not drawn to scale.