1887  Thalassoceras Gemmellaro: 69.
     1889  Thalassoceras.- Karpinsky: 80.
     1919  Thalassoceras.- Böse: 102.
     1937  Thalassoceras.- Plummer & Scott: 357.
     1948  Prothalassoceras.- Maximova: 23.
     1957  Thalassoceras.- Treatise: L68.
     1960  Thalassoceras.- Ruzhentsev: 206.
     1962  Thalassoceras.- Osnovy: 370.
     2002  Thalassoceras.-Leonova: S39.

Type species: Thalassoceras phillipsi Gemmellaro, 1887, p.71 [SD Plummer & Scott, 1937, p.357].

A:   Conch form subdiscoidal, with very narrow or closed umbilicus.
G:   Digitation of suture-line reaching saddles. Adventitious lobe wider than prongs of ventral lobe; saddles narrowly rounded.