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Amphistegina
Classification
Phylum:
Protista
Subphylum:
Sarcodina
Class:
Reticularea
Subclass:
Granuloreticulosia
Order:
Foraminiferida
Suborder:
Rotalina
Superfamily:
Orbitoidacea
Family:
Amphisteginidae
Formal Genus Name and Reference:
Amphistegina D'ORBIGNY, 1826, *1391, p. 304
Type Species:
A. vulgaris, SD Parker, Jones & BRADY, 1865, *1419, p. 36
Images
(Click to enlarge in a new window)
Fig. 549, 1. A. gibbosa d'Orbigny, Rec., W.Indies, Ia-c, ext. views, X30 (*2110)"
Synonyms
Omphalophacus
Geographic Distribution
cosmop.
Age Range
Beginning Stage in Treatise Usage:
U.Cret., Eoc.
Beginning International Stage:
Cenomanian
Fraction Up In Beginning Stage:
0
Beginning Date:
100.5
Ending Stage in Treatise Usage:
Rec.
Ending International Stage:
Meghalayan
Fraction Up In Ending Stage:
100
Ending Date:
0
Description
Lenticular, generally unequally biconvex, with low turbinoid spire, multichambered, chambers equitant, with alar prolongations as in Nummulites, dorsal septa simple, radiate, falciform, and may undulate near umbo, ventral septa divided by deep, commonly imbricate constrictions forming secondary lobes that have appearance of secondary chamberlets in rosette around umbo; walls thick, laminated. and traversed by pores (*223, *1391, *1419).
References
Museum or Author Information
Classification
Phylum:
Protista
Subphylum:
Sarcodina
Class:
Reticularea
Subclass:
Granuloreticulosia
Order:
Foraminiferida
Suborder:
Rotalina
Superfamily:
Orbitoidacea
Family:
Amphisteginidae
Formal Genus Name and Reference:
Amphistegina D'ORBIGNY, 1826, *1391, p. 304
Type Species:
A. vulgaris, SD Parker, Jones & BRADY, 1865, *1419, p. 36
Images
(Click to enlarge in a new window)
Fig. 549, 1. A. gibbosa d'Orbigny, Rec., W.Indies, Ia-c, ext. views, X30 (*2110)"
Synonyms
Omphalophacus
Geographic Distribution
cosmop.
Age Range
Beginning Stage in Treatise Usage:
U.Cret., Eoc.
Beginning International Stage:
Cenomanian
Fraction Up In Beginning Stage:
0
Beginning Date:
100.5
Ending Stage in Treatise Usage:
Rec.
Ending International Stage:
Meghalayan
Fraction Up In Ending Stage:
100
Ending Date:
0
Description
Lenticular, generally unequally biconvex, with low turbinoid spire, multichambered, chambers equitant, with alar prolongations as in Nummulites, dorsal septa simple, radiate, falciform, and may undulate near umbo, ventral septa divided by deep, commonly imbricate constrictions forming secondary lobes that have appearance of secondary chamberlets in rosette around umbo; walls thick, laminated. and traversed by pores (*223, *1391, *1419).