Endodermal Sphincter: Sphincter muscles lying entirely outside the mesoglea of the column itself, the muscle processes project into and are clothed entirely by endoderm (Stephenson 1928; p. 10). Three different forms: diffuse, restricted or circumscript.

Image of an Endodermal Sphincter: (species names are linked to the Hexacorallian database)

Species: Tealia piscivora

Caption: Fig. 3. A) *Tealia piscivora*, circumscribed endodermal sphincter

Species: Paranemonia vouliagmeniensis

Caption: *Fig. 2. Paranemonia vouliagmeniensis* sp.n. - A. Vertical section showing diffuse endodermal sphincter (*arrow*).