Fig. 1. Embryonic and periembryonic chambers in Orbitoides spp. according to Van Hinte's 1966 concept. I: protoconch; II: deuteroconch; PAC: principal auxiliary chamber; PEC: principal epi-auxiliary chamber; AEC: accessory epi-auxiliary chamber. In our view, we prefer to call PAC an auxiliary and AEC an adauxiliary chamber; (Hottinger, 2006; fig. 4  CC/BY-NC-SA)
Fig. 2. Development of chamberlet cycles from an auxiliary chamber in an early orbitoid, the Campanian Lepidorbitoides minima H. Douvillé from Mexico, after Aguilar et alii, 2002. A: stereograph of a megalospheric embryo consisting of a biconch (protoconch and deuteroconch) supplemented by a third chamber (auxiliary chamber) with a median and two lateral stolons. Successive growth stages coloured alternately in red and blue. Lamellation omitted. Schematic, not to scale. A: auxiliary chamber; D: deuteroconch; P: protoconch; ; lst: lateral stolon; mst: median stolon; (Hottinger, 2006; fig. 36a  CC/BY-NC-SA)
- according to Hottinger (2006):
AUXILIARY CHAMBER - (= auxiliary chamberlet); a chamber or a chamberlet fed by a stolon positioned in the suture between protoconch and deuteroconch in orbitoidiform foraminifers. May be double in embryos with a bilateral symmetry or multiple, when the protoconch and the deuteroconch have additional equatorial stolons. Together with the adauxiliary chamberlets, they form a corona.
Aguilar, Bernaus, Caus & Hottinger (2002), Lepidorbitoides minima DOUVILLÉ from Mexico, a foraminiferal index fossil for the Campanian, Journal of foraminiferal Research, Lawrence, vol. 32, N° 2, p. 126–134.
Van Hinte (1966), Orbitoides from the Campanian type section. Part I., Koninklijke Nederlandse Akademie van Wetenschappen, Proceedings, Amsterdam, (Series B), vol. 69, N° 1, p. 79-110.
Hottinger (2006), Illustrated glossary of terms used in foraminiferal research. Carnets de Géologie, Memoir 2, ISSN 1634-0744
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