Materia medica

[Richard Ellis <richellis@nyc.rr.com>]

The "materia medica" was the list of pharmacological preparations used in 
various systems of medicine. I'm trying to write about the similarities of 
the Chinese materia medica with the medieial European version, but I don't 
know the plural of "materia medica." Can any of the linguists on this list 
provide me with the plural form?

Oh yes, to bring this letter into the realm of early reptiles, my "Sea 
Dragons: Predators of Prehistoric Oceans" has just been published by the 
University Press of Kansas.

Thanks,

Richard Ellis