The West Indian giant rice rats are divided into three species: M. desmarestii (Martinique), M. audreyae (Barbuda), and M. luciae (St. Lucia).  M. desmarestii, the largest of the three, survived into the earliest 20th century and is known from live-caught museum specimens. It had a body measurement of 360 mm and a tail that measured about 330 mm.  The fur on the underside and base of the tail was white, while its head and back were black or dark reddish brown.  In addition the fur on this animal was long, stiff, and sometimes shiny.  M. luciae, which survived into the mid 19th century and is also known from live-caught museum specimens, was smaller and almost completely brown.  M. audreyae is known only from a fossil hemimandible and isolated incisor tooth of   unknown age. Closely related rodents from the subfossil records of Antigua and Guadeloupe are currently under study (Flemming and McFarlane, 1997).