1929  Thalassoceras (Prothalassoceras) keytei Smith: 176.
     1940  Eothalassoceras keytei.-Miller & Furnish: 105.
     1950  Eothalassoceras keytei.-Miller & Downs: 207.

Two small rounded longitudinal grooves on the ventro-lateral zone of the conch.

[Possibly elder synonym of E. kingorum Miller (teste Miller & Downs, 1950, p.207)].