- macquarrii
- macrocephala
- macrocephaly
- macrochromosomes
- Macroclemys
- macromolecules
- macrospilota
- macrurus
- maculosa-type
- madagascariensis
- magdalense
- major
- Malaclemys
- Malacochersus
- Malayemys
- malonei
- Malpighian cells
- mandible
- manni
- Manouria
- marbled
- marginal scutes
- marginata
- marmorata
- marokkensis
- masseteric scale
- Mauremys
- mawii
- maxilla
- maximiliani
- mccordi
- Meckel's cartilage
- medial
- megacephalum
- megaorder
- melanism
- Melanochelys
- melanonota
- melanophores
- melanosterna
- membrane
- mertensi
- Mesoclemmys
- mesoderm
- mesoplastra
- metabolism
- metacentric
- metteri
- mexicana
- miaria
- microchromosomes
- microphyes
- mimicry
- minor
- mitotic
- mobilensis
- monophyletic
- monotypic
- Morenia
- mottled
- mouhotii
- mtDNA
- muhlenbergii
- murrayi
- mutica
- muwayi
- Myanmar
- mydas