  One generalization of ordinary matroids is symplectic matroids. While
symplectic matroids were initially defined by their collections of bases, there
has been no cryptomorphic definition of symplectic matroids in terms of
circuits. We give a definition of symplectic matroids by collections of
circuits. As an application, we construct a class of examples of symplectic
matroids from graphs in terms of circuits.
