. Bulletins of American paleontology. Devonian Rugose Corals of Iowa: Sorauf 69 26 28 30 32 34 36 38 Colony Mean Diameter of Tabularium - mm Texl-tigure 41.—Hexagonaria inequalis from the "rusty bed" oi the Cerro Gordo Member, colony mean diameter of tabularium (in mm) plotted versus the colony mean for total number of septa in each corallite. The small diameter holotype of H. inequalis is here indicated, as well as that of Hexagonaria whirfieUli. here regarded as a junior synonym. in the outer dissepimentarium, but with major septa that extend to corallite axes and either join
. Bulletins of American paleontology. Devonian Rugose Corals of Iowa: Sorauf 69 26 28 30 32 34 36 38 Colony Mean Diameter of Tabularium - mm Texl-tigure 41.—Hexagonaria inequalis from the "rusty bed" oi the Cerro Gordo Member, colony mean diameter of tabularium (in mm) plotted versus the colony mean for total number of septa in each corallite. The small diameter holotype of H. inequalis is here indicated, as well as that of Hexagonaria whirfieUli. here regarded as a junior synonym. in the outer dissepimentarium, but with major septa that extend to corallite axes and either join or leave an extremely small open axial space (, ). The thick septa are dilated somewhat and make an almost solid ring around the outer tabularium by addition of stereome coating of the inner flank of the dissepimen- tarium. Intercorallite walls either are straight where stout septa of neighboring individuals are opposed, or slightly wavy where septa are offset in neighboring corallites. In many corallites the major septa are dilat- ed by up to 50% in the innermost dissepimentarium; equally thick minor septa are not dilated, but simply retain their thickness throughout the dissepimentarium and tabularium. The second morphotype in this species is one with greater distance between corallite axes and broader dissepimentaria (, ). Colonies of this type have septa that are thinner in the outer dissepimentar- ium, and intercorallite walls are straight. Septa may have swollen trabeculae in the outer dissepimentarium giving a carinate appearance, and dissepiments are large and globose in this area. Where these thinner septa are at all thickened, there is a resulting broader base at the wall, so that a series of triangular bases is present, buttressing the walls. These also have marked dilation in the inner dissepimentarium, but more spin- dle-shaped dilation, as typical in many species of this genus. Dilation is typically two to three times septal thickness in the
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