Cardium ainuanum Yokoyama, 1927 † accepted as Clinocardium ainuanum (Yokoyama, 1927) † (new combination reference)
Cardium taracaicum Yokoyama, 1930 † accepted as Clinocardium taracaicum (Yokoyama, 1930) † (new combination reference)
Cerithium proavitum Yokoyama, 1929 † accepted as Batillaria (Tateiwaia) yamanarii Makiyama, 1926 † represented as Batillaria W. H. Benson, 1842 (source of synonymy)
Cerithium tokudai Yokoyama, 1930 † accepted as Bittium tokudai (Yokoyama, 1930) † (new combination reference)
Chrysodomus despectus var. tuberculata Yokoyama, 1929 † accepted as Neptunea tuberculata (Yokoyama, 1929) (new combination reference)
Mactra makiyamai Yokoyama, 1928 accepted as Serripes makiyamai (Yokoyama, 1928) † (new combination reference)
Natica kiritaniana Yokoyama, 1931 † accepted as Neverita kiritaniana (Yokoyama, 1931) † (new combination reference)
Pectunculus derelectus Yokoyama, 1928 † accepted as Glycymeris derelectus (Yokoyama, 1928) † (new combination reference)
Pleurotoma declivis f. striatotuberculata Yokoyama, 1928 † accepted as Bathytoma striatotuberculata (Yokoyama, 1928) (new combination reference)
Potamides nyemurai Yokoyama, 1929 † (status source)
Solariella sakya Yokoyama, 1931 † accepted as Minolia sakya (Yokoyama, 1931) † (new combination reference)
Strombus mimasakensis Yokoyama, 1929 † (status source)
Tapes uyemurai Yokoyama, 1927 † accepted as Clementia uyemurai (Yokoyama, 1927) † (new combination reference)
Venus okadana Yokoyama, 1932 † accepted as Pitar okadanus (Yokoyama, 1932) † (new combination reference)
Voluta koyuana Yokoyama, 1928 † accepted as Lyria koyuana (Yokoyama, 1928) † (new combination reference)