(de Man, 1895)
Carapace transversely hexagonal, dorsal surface generally smooth; cardiac and branchial regions traversed by a transverse ridge and continued into a branchial ridge which is curved forwards laterally; short transverse ridges also on the gastric region and on either hepatic regions. Frontal margin somewhat broader than orbit, obscurely bilobate; upper orbital border slightly sinuate, transverse; external orbital angle triangular and projecting forwards; lateral borders cristate and entire. Meri of ambulatory legs not very broadish, their dorsal surfaces with a curved longitudinal ridge behind the anterior border. (Türkay 1995)
Type locality: Tokyo Bay, Japan.
Range: Japan - Tokyo Bay (Ortmann, 1894a, de Man, 1895a), Asadokoro, Tokyo Bay, Shimoda, Aichi Prefecture and Nagasaki (Sakai, 1939), Mutsu Bay, Jusan-gata, Hachiro-gata, Tokyo Bay, Shimoda, Mikawa Bay, Ise Bay, Nagasaki, and Ariake Bay (Sakai, 1976a), Midori-gawa, Kumamoto (Miyake, 1983), Usu and Mokoto Lake, Hokkaido (Komai et al., 1992); Korea - (Sakai, 1939, Kamita, 1941), Kanghwa Island and Bangjugpo (Kim, 1970), Bangjugpo and Seondu Ri (Kim, 1973); China - Bo Hai and Shandong Peninsula (Shen, 1932), Tsimei, Fujian Province (Shen, 1940b), Fujian (Dai& Yang, 1991); muddy coast at inland sea or river mouth.