Sigmoilina

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Sigmoilina is a miliolid genus, referring to the foraminiferal order Miliolida, characterized by an assymmetricall biconvex test formed by strongly overlapping chambers, one-half coil in length, that form a sigmoid (S-shaped) curve in cross section. The strongly overlapping chambers obliterate earlier ones from view resulting in the compressed biloculine appearance, differing from the squat, depressed biloculine form of and . The test, as for all Miliolida, is porcelaneous and imperphorate, the terminal aperture, with tooth, the only point of egress and ingress for the animal.

Sigmoilina is a protist, or proctoctist according to B.K. Sen Gupta, 1999, included in the miliolid family Hauerinidae (Loeblich & Tappan, 1988). It was previously assigned to the Miliolidae (Loeblich & Tappan, 1964) when foraminfera were regarded as comprising a suborder (Foraminiferida).

References[]

• Alfred R. Loeblich Jr and 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.
• Alfred R. Loeblich Jr and Helen Tappan, 1988. Forminiferal Genera and their Classification.
• Barun K. Sen Gupta 1999. Modern Foraminifera.
• Sigmoilina in Fossilworks (Paleo db)