Holotype and paratypes of C. tsudai and holotype of C. pacifica. A Holotype (RMNH.5004167) and B–I paratypes (RMNH.5004168-72) of C. tsudai and J holotype of C. pacifica (RGM 458.690) photographed in a ventral view. Photographs of RMNH.5004169-72 from Burridge et al. (2015); RMNH.5004167-68 taken by R. van der Hulst and RGM 458.692 taken by E.F. de Vogel, this study. RMNH = Naturalis Biodiversity Center, mollusc collection and RGM = Naturalis Biodiversity Center, fossil planktonic mollusc collection, Leiden.