The Hamilton's frog (Leiopelma hamiltoni) is a primitive frog native to New Zealand, one of only four extant species belonging to the family Leiopelmatidae. New Zealand's frog species all are in the family Leiopelmatidae. The male remains with the eggs to protect them and allows the tadpoles to climb onto his back where they are kept moist. It is named in honour of Harold Hamilton the collector of the type specimen. The holotype is in the collection of the Museum of New Zealand Te Papa Tongarewa. Description They are mostly light brown in colour, although some green individuals have also been observed. A single dark stripe runs along each side of the head and through the eye. There is no webbing between the hind toes, and the fingers are not webbed. These frogs have a snout length of 5.5 mm, and thighs that can reach up to 14.8 mm. Leiopelma hamiltoni is a very small frog species, with males being even smaller than females. Males have a snout-vent length of up to 43 millimeters and up to 49 millimeters for females. They are typically a brown color which can range from very light brown to almost black. Some have also been spotted having a green color. They also have black spots covering their bodies. Unlike other frogs, they have very little to no webbing on their hind toes and also do not have external eardrums. They have a row-like design down the back and sides of their body which are made up of callus-like glands in their skin. This coloration allows the frogs to blend in well with their surroundings. These rows start right at the back side of the eye, with the middle row being the largest and most distinct. The end of this middle row terminates at what scientists called the paratoid gland. The lines are also seen on the legs, feet, and arms but are less prominent than the ones on its back. Distribution Hamilton's frog live only on a small rocky area on mammal-free Stephens Island in the Cook Strait. Sub-fossils indicate Hamilton's frog once lived throughout the lower North Island and upper South Island. They live around rocky, moist and grassy areas. Leiopelma hamiltoni are typically found on the Stephens and Maud Islands, located in the Marlborough Sounds region of New Zealand. Maud island is very small with steep hills, only spanning about 760 acres.