Fossils of most species are found primarily in
Upper Cretaceous strata of Japan.
N. mirabilis is found in
Coniacian-aged strata of Japan and possibly
Turonian-aged strata in Madagascar.
N. bacchus is found in Upper Cretaceous Hokkaido. Two species are found exclusively outside Japan,
N. sachalinensis, which is found in Upper Cretaceous strata of Sakhalin island, and Kamchatka peninsula, and
N. occidentalis, which is known from two shells found in the
Turonian-aged
Hornbrook Formation of Southern Oregon. == In popular culture ==