a subclass of extinct colonial spineless animals of the coral polyp class. They existed from the late Ordovician period until the middle Devonian. The Helioloitidea had a massive calcarious skeleton consisting of tubes called corralites. The cavity in each corralite was crossed by numerous transversal calyces; from within protruded 12 vertical partitions (septa). The space between the separate corallites was filled by the interstitial skeleton, the coenenchym. This structure consisted of calcarious calyculi (dissepiments), fine tubes, or vertical rods (trabecula). The subclass is subdivided into eight families, comprising 30 genera. The Heliolitoidea were found in the shallow waters *of nearly all the earth’s seas.
REFERENCESokolov, B. S. “Podklass Heliolitoidae.” In Osnovy paleontologii: Gubki, archeotsiaty, kishechnopolostnye, chervi. Moscow, 1962.
R. L. MERKLIN