Is there such a word as apparati?

As I understand it,an apparati (as in reference to a single individual) makes up a set of apparatus (a number of apparati that come together to form the apparatus). Whether this is right or wrong I am not sure.

I used this Word in the following sentence in reference to rotifers.

"The mastax contains a complete set of masticating apparati, or hard chitinous jaws, which are commonly referred to as trophi."

Karl W. Schwab