  We discuss general incompressible inviscid models, including the Euler
equations, the surface quasi-geostrophic equation, incompressible porous medium
equation, and Boussinesq equations. All these models have classical unique
solutions, at least for short time. We show that they have real analytic
Lagrangian paths. More precisely, we show that as long as a solution of any of
these equations is in a class of regularity that assures H\"{o}lder continuous
gradients of velocity, the corresponding Lagrangian paths are real analytic
functions of time. The method of proof is conceptually straightforward and
general, and we address the combinatorial issues head-on.
