We study the exceptional U-duality group E-d of M-theory compactified
on a d-torus and its representations using Matrix theory. We exhibit t
he E-d structure and show that p-branes wrapped or unwrapped around th
e longitudinal direction form representations of the U-duality group t
ogether with other, more mysterious, states. (C) 1998 Elsevier Science
B.V.