spiral valve n.
See spiral fold of cystic duct.
The ductus choledochus opens on the ventral side of the intestine immediately in front of the commencement of the spiral valve.
The shell of this animal consists of one spiral valve, divided into several apartments.
A spiral valve is also present in the more ancient types of the true fishes as dipnoans, crossopterygians, and ganoids.
The presence of a spiral valve; though this character may possibly break down with the extension of our knowledge.