A new ovoviviparous species, Echininus viviparus, inhabiting high intertidal and supratidal areas in the Mariana Islands is described in the littorinid subfamily Echininae which previously consisted of the polytypic Indo-Pacific species Echininus cumingi (Philippi, 1846) and the West-Atlantic species Tectininus nodulosus (Pfieffer, 1839). Characteristics of the subfamily are reviewed.