In the modern Bahamas and Caicos Banks, muddy tidal flats develop just in the lee side of the larger islands, very close to high-energy marginal areas. In these cases, sedimentary models are quite similar to the barrier-island ones and they show the contemporaneous presence of high and low-energy facies in the windward side of the bank. The importance of these models on the paleoenvironmental interpretation of the Mesozoic platforms of the Apennines are not yet fully evaluated and many facies descriptions are largely inspired to a model of carbonate platform attached to land masses, as the Florida Bay. Mesozoic platforms of the Apennines were instead isolated from the continental areas from the Lower Jurassic. In this case, the terms "inner" and "outer" platform, in order to define low and high energy facies, are deceptive because they contain an interpretation that attributes a wrong polarity to the platform. A right interpretation of the sedimentary environment of some muddy tidal facies allows to detect the presence of the couple "island and tidal flat" and to recognize the windward side of the platform. This result should provide basis to define the architecture of the carbonate bank, the trend of the dominant winds, the trend of the wind-driven currents and also it should justify the existence of some particular coarsening-upward cycles with high-energy sand flat facies overlying muddy tidal flat facies.