Megalomys desmarestii, also known as the Martinique muskrat, Desmarest's pilorie, or the Martinique giant rice rat, It may have been semi-aquatic, as it was known to escape into the sea when pursued by predators, but it never swam away from the island.
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Extinction
It was common on Martinique until the end of the 19th century, when attempts were made to exterminate it because it was considered to be a pest of the island's coconut plantations in the southern units of the country. It was also hunted for food; however, due to its strong musky odor, this was uncommon. On 8 May 1902, the volcano Mount Pelée erupted, completely destroying the island's principal city of Saint-Pierre. Predation by introduced small Indian mongooses is was likely the primary cause of the muskrat's extinction, but the eruption has been speculated to have been the factor that finally drove it to extinction.