The Miocene deposits of the West Indies and Central America are famous for molluscan faunas having the richness and brilliancy characteristic of tropical faunas. Probably more than 2,000 species of mollusks have already been collected from these deposits, but not more than half of them have been described. The middle Miocene (Helvetian) beds, usually carry larger faunas than other Miocene deposits. Middle Miocene faunas of 400 to 600 species have been discovered in the Dominican Republic, Jamaica, Costa Rica, and Panama.
Most of the tropical Miocene faunas from the West Indies and Central America are different from the subtropical and temperate faunas of the same age along the Gulf and Atlantic coasts of the United States. The lower Miocene (Burdigalian) faunas of the West Indies resemble the subtropical fauna of the Chipola marl (Burdigalian) of Florida; but the West Indian middle . . .