Ephippium \E*phip"pi*um\, n. [L., saddle cloth, fr. Gr. ?; 'epi` on + ? horse.]

1. (Anat.) A depression in the sphenoid bone; the pituitary fossa.

2. (Zo["o]l.) A saddle-shaped cavity to contain the winter eggs, situated on the back of Cladocera.

Source: Webster's Revised Unabridged Dictionary (1913)