Spirocyclina

Spirocyclina; Temporal range: Late Cretaceous (Santonian)
Scientific classification
Domain:	Eukaryota
(unranked):	SAR
(unranked):	Rhizaria
Phylum:	Retaria
Subphylum:	Foraminifera
Class:	Rotaliata
Order:	Loftusiida
Family:	Spirocyclinidae
Genus:	Spirocyclina; Munier-Chalmas, 1887

Spirocyclina is a genus of large forams, with a flat test as much as 10mm in diameter. Coiling is planispiral to slightly asymmetric and mostly involute, some becoming uncoiled with a straight final stage. The final whorl, or stage, has about 25 strongly arcuate chambers. Composition is of agglutinated matter, the outer layer of the wall imperforate. Chambers are subdivided into secondary chamberlets by internal structures. The aperture consists of a double row of pores on the apertural face. Anchispirocyclina and Martiguesia are among related genera.

References

Alfred R. Loeblich, jr & Helen Tappan 1964. Sarcodina, Chiefly "Thecamoebians" and Foraminiferida. Treatise on Invertebrate Paleontology, Part C, Protista 2. Geological Society of America and University of Kansas Press.
A.R. Loeblich & H Tappan, 1988 in GSI.ir Paleontology.
Rotaliata, Textulariana

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