  Two common misconceptions about the theory of Special Relativity that are
actively taught in textbooks are discussed. It is shown, first, that the
Lorentz transformations are actually transformations of the coordinates of a
photon, not the coordinates of a particle as taught by some authors. Secondly,
a misconception concerning the relativistic Lagrangian is discussed. It is
shown that the currently accepted formulation of the Lagrangian is missing an
important constant of integration. By incorporating the missing constant of
integration, the new Lagrangian directly supports the conclusions reached
previously by the author concerning the mass-energy equivalence principle.
