Abstract: | Linear relativistic wave equations of Bhabha's type are discussed. Conditions for unique mass and unique spin are analysed in detail. It is shown that if one relaxes the diagonalisability of βo by a weaker block form one gets a class of equations describing a spin-half particle. Several algebras which emerge and their representations are studied. The existence or otherwise of the hermitianising matrix in such cases is explicitly discussed. The properties of the new equations in the presence of minimally coupled electro-magnetic field are discussed. |