Megalomys luciae
Megalomys luciae, also known as the Saint Lucia pilorie or Saint Lucia giant rice-rat, as well as several variant spellings, is an extinct rodent that lived on the island of Saint Lucia in the eastern Caribbean. Description 
It was the size of a small cat, and it had a darker belly than Megalomys desmarestii, a closely related species from Martinique, and slender claws. Other physical features include brown/ochre dorsal coloration and white soft fur patches. Individuals had webbed hind feet, smooth heels with interdigital pads. Their tail was longer than the length of the body from head to toe; the tail contained sparse hairs and was mainly covered with epidermal scales. Their skulls were very delicate with an amphora shape. Extinction 
The last known specimen died in the London Zoo in 1852, after three years of captivity. It probably became extinct in the latter half of the 19th century due to introduction of the invasive small Indian mongoose, with the last record dating from 1881, right before mongoose introduction. There is a stuffed specimen in the collection of the Natural History Museum in London. References

Rodent extinctions since 1500
Mammals of Saint Lucia
Megalomys
Mammals described in 1901