Porina gracilis is found in the Recent and Tertiary of southeastern Australia. It is a common component of shelf faunas across a wide depth range.
Part of a colony lobe, width about 2 mm. An ovicell is present near the centre of the image, immersed in porous frontal calcification. Secondary orifices are visible: the primary orifices are hidden at the lower end of long peristomes. A slit-like spiramen opens proximal to the secondary orifice; this leads to an opening in the peristome above the proximal margin of the primary orifice. Small avicularia are visible at the margins of the secondary orifices. |
Additional SEM images provided by D. Gordon and NIWA.
Original description: Eschara gracilis Lamarck, 1816
Locality: Australia
Type specimen: