Clymenia is a genus in the ammonoid order Clymeniida, restricted to the Upper Devonian, characterized as with all clymeniids by a dorsal siphuncle that runs along the inside of the whorls, unusual for ammonoids.

Clymenia has a closely coiled evolute shell that may be faintly ribbed.

The suture is simple, with a broad ventral saddle, broad lateral lobe, a dorso-lateral saddle, and a moderately deep hidden dorsal lobe.

Septal necks are usually short and do not form a continuous tube.

Clymenia is type genus of the family Clymeniidae.