  We present a computer simulation study on the crystalline phases of hard
ellipsoids of revolution. For aspect ratios greater than or equal to 3 the
previously suggested stretched-fcc phase [D. Frenkel and B. M. Mulder, Mol.
Phys. 55, 1171 (1985)] is replaced by a novel crystalline phase. Its unit cell
contains two ellipsoids with unequal orientations. The lattice is simple
monoclinic. The angle of inclination of the lattice, beta, is a very soft
degree of freedom, while the two right angles are stiff. For one particular
value of beta, the close-packed version of this crystal is a specimen of the
family of superdense packings recently reported [Donev et al., Phys. Rev. Lett.
92, 255506 (2004)]. These results are relevant for studies of nucleation and
glassy dynamics of colloidal suspensions of ellipsoids.
