Holasaphus centropyge Matthew, 1895, the type species of the genus, is redescribed using known and new material from the Middle Cambrian of Nova Scotia. A new species, Holasaphus mesopotamicus, described from the Derik–Mardin district of southeastern Turkey, marks the only other known occurrence of the genus. The presence there of Holasaphus and the agnostid Peronopsis in the middle portion of the Sosink Formation suggests that the latter may be no younger than Middle Cambrian and lends additional support to evidence for the probable regional absence of Upper Cambrian strata.

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