Mesothuria (Zygothuria)

Perrier, 1898

3 species

thirteen to 20 tentacles, madreporite placed close to body wall, without penetrating it. Body ovoid, integument often wrinkled, not flattened but with a well differentiated sole. A single series (rarely 2 series) of feet in each latero-ventral ambulacrum, placed on the margin of the sole. These appendages are widely spread; dorsally, very small papillae, not numerous, irregularly distributes and sometimes absent. Calcareous deposits of integument exclusively in form of tables; either tri- or quadri- radiate. From Perrier, 1901 for Zygothuria. (Deichmann 1930). The genus Zygothuria is disputed by Sluiter & Hérouard. (Deichmann, 1930, for Zygothuria)

Body flat with pedicels arranged exclusively in a single or double row along the paired ambulacrum those of the dorsal side often minute., A marginal fringe often present. Tables of the body wall with normally three long spines, only occasionally one or two spines. From key. (Heding, 1942)

now It does not seem necessary to retain Zygothuria, even as a subgeneric name. (Pawson, 1965)