- The hydrodynamics of biaxial nematics has been obtained in the presence of an external field H. By working with the triad order parameter, we obtain results valid for arbitrary nonsingular textures. We also present the bending energy for biaxial nematics. Our derivation of the hydrodynamics explicitly includes angular momentum conservation. The resulting hydrodynamic equations clearly possess a rotating-equilibrium solution. In an Appendix we discuss extending the theory to include the internal angular momentum of the molecules which constitute the biaxial nematic. 1982 The American Physical Society.