Comparison of mitochondrial gene organizations of snakes. Gene arrangements are presented for the following six types of snakes. I: Ramphotyphlops braminus; II:Leptotyphlops dulcis; III: Naja naja, Acrochordus granulatus, Boa constrictor, Cylindrophis ruffus, Python regius, Xenopeltis unicolor; IV: Dinodon semicarinatus, Pantherophis slowinskii, Enhydris plumbea; V: Ovophis okinavensis; VI: Deinagkistrodon acutus, Agkistrodon piscivorus. L1, L2, S1, S2. P* represent genes for trnL(UUR), trnL(CUN), trnS(AGY), trnS(UCN), and a pseudogene for trnP. tRNAs transcribed from the gene-rich and gene-poor strand were specified by noting their names above and below the gene map respectively. The tree topology on the right side was simplified from Fig. 2.