We study generalisations of the XXX-model to higher rank underlying symplec
tic algebras in the semi-classical approximation. With the help of the meta
plectic representation of sp(2n, R) we establish general results that are u
seful in the analysis of these algebras, and hence solve the algebraic Beth
e ansatz explicitly in this representation. The su(n) multiplet structure o
f the Bethe eigenstates is revealed.