Comparison of the gene order of the four known stylommatophoran mitogenomes. For each mitogenome genes above the horizontal line are transcribed from left to right; genes below the horiziontal line are transcribed from right to left. TRNAs are denoted by their one-letter abbreviations. The diagonal lines indicate mitochondrial gene rearrangements between the specified taxa. In the gene-map of C. obtusus, I-III indicate three unassigned regions (see Figure 1 and Discussion). Gene sizes are not drawn to scale.