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Didymocyrtis penultima (Riedel, 1957)

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Cortical twin-shell, shell constricted equatorially, with circular to irregularly rounded pores: its surface bearing prominent, obtuse protuberances. Distal chambers hemispherical, as caps on either end of cortical twin-shell, their length usually 0.2-0.3 that of twin-shell, somewhat narrower than twin-shell. Each cap surmounted by a spongy tube or tongue-shaped column, of which the width is approximately half that of the maximum breadth of twin-shell, or less. Outer medullary shell lenticular, inner one spherical. Length of cortical twin-shell usually 100-120µ, its maximum breadth 80-105µ. Length of polar caps 25-40µ, of spongy polar columns 25-80µ.
This species differs from other described members of the genus in the heavy protuberances of the cortical twn-shell.
(Riedel) 1957











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