Genus Xenotrypa Bassler, 1952

TYPE SPECIES. — Fistulipora primaeva Bassler, 1911 by subsequent designation (Bassler 1952). Lower Ordovician (?Arenig); Russia.

DIAGNOSIS. — Massive or encrusting colonies. Autozooecia slightly indented by acanthostyles. Diaphragms in autozooecia few to absent. Vesicles irregular, isolating autozooecia. Acanthostyles large, generally in autozooecial walls, some in vesicle walls; centres light to dark in colour. Autozooecial walls indistinctly laminated.

OCCURRENCE. — Lower to Middle Ordovician of Russia and Argentina.

COMPARISON

Xenotrypa Bassler, 1952 differs from Hennigopora Bassler, 1952 in acanthostyles which do not significantly indent into the autozooecia, whereas acanthostyles in Hennigopora strongly indent autozooecia. Furthermore, vesicles usually completely isolate autozooecia in Xenotrypa, whereas the autozooecia in Hennigopora often share a common wall.