We consider the cohomology group associated with Jacobi cusp forms ove
r Cayley numbers as an example of the general theory of the cohomology
groups associated with cusp forms developed by Eichler and Shimura. T
he theory establishes isomorphisms between the cohomology groups and t
he vector spaces of vector-valued cusp forms and then expresses their
common dimensions in terms of certain geometric invariants in the corr
esponding quotient spaces. This is an analogue of the Riemann-Roch the
orem applied to the cases of vector-valued modular forms.