''Clymenia'' is a genus in the

ammonoid Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

order

Clymeniida Clymeniida is an order of ammonoid cephalopods from the Upper Devonian characterized by having an unusual dorsal siphuncle. They measured about in diameter and are most common in Europe, North Africa, and South China but are known from North ...

, restricted to the Upper Devonian, characterized as with all clymeniids by a dorsal

siphuncle The siphuncle is a strand of biological tissue, tissue passing longitudinally through the mollusc shell, shell of a cephalopod mollusc. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the li ...

that runs along the inside of the whorls, unusual for ammonoids. ''Clymenia'' has a closely coiled evolute shell that may be faintly ribbed. The dorsum, on the inside of the whorl, is slightly impressed, a result of the outermost whorl slightly enveloping the previous. The venter may be rounded or acute. 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. The suture and siphuncle are characteristic of the family. ''Clymenia'' is type genus of the family Clymeniidae. Is fossils have been found in Europe and Western Australia.

References

;Notes ;Bibliography * ''Rocks, Minerals & Fossils of the World'' by Chris Pellant and Roger Phillips * ''

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

, Part L Ammonoidea''; Geological Society of America and Univ of Kansas Press, 1964 Late Devonian ammonites Ammonites of Australia Ammonite genera Clymeniina {{Clymeniida-stub