View source for Pigeon-hole

[[File:Fig 45.jpg|thumb|<font size="2">'''Fig. 1.''' Alveolar exoskeleton and polygonal network.
'''A-C:''' simple alveolar layer in ''Everticyclammina virguliana'' (Koechlin), Mechra Klila, Northeastern Morocco, Uppermost Jurassic. '''A:''' stereograph, schematic, not to scale. '''B:''' tangential section. Note the large size of the alveoles in a postseptal position. '''C:''' para-equatorial, non-centered section showing septa and the basal coat at the bottom of the chamber, resembling a basal layer. '''E-G:''' polygonal network in ''Spirocyclinidae''. '''E:''' ''Choffatella tingitana'' Hottinger, megalospheric generation, in tangential section near to the equatorial plane. Note the clear differentiation of beams and rafters. '''D:''' stereograph of spirocyclinid polygonal network. Note the curved pigeon holes in preseptal position which in axial section might be mistaken for foramina. '''F-G:''' extension of beams into a corrugated sheet that replaces endoskeletal pillars in ''Hottingertidae''. '''F:''' stereograph representing a part of an axial section. Not to scale. '''G:''' ''Alveosepta powersi'' (Redmond), Northeastern Morocco, Upper Jurassic. Equatorial section of megalospheric specimen.
'''alv:''' alveoles; '''b:''' [[beam]]; '''bl:''' [[basal layer]]; '''corr:''' corrugated median extension of beams; '''f:''' [[foramen]]; '''ph:''' pigeon holes; '''s:''' [[septum]]; '''sf:''' supplementary foramina; '''sph:''' [[sphaeroconch]]; '''ssut:''' [[septal suture]]. '''Arrows:''' direction of growth. After Hottinger, 1967.; (Hottinger, 2006; fig. 45 [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]]
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==Definition==
*''according to Hottinger (2006):''
'''PIGEON-HOLE ''' - an alveolar cavity in the exoskeletal polygonal network that expands at its blind end below the [[epiderm]] into a polygonal shape. Its opening into the chamber cavity is delimited by longer [[beam]]s (perpendicular to the septum) and by shorter [[rafter]]s (parallel to the septum). 

==See also==
* [[beam]]
* [[epiderm]]
* [[exoskeleton]]
* [[rafter]]


==References==
Hottinger (1967), Foraminifères imperforés du Mésozoïque marocain, Notes et Mémoires du Service géologique, Rabat, N° 209, p. 5-168

Hottinger (2006), [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Illustrated glossary of terms used in foraminiferal research]. [http://paleopolis.rediris.es/cg/uk-index.html Carnets de Géologie], [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Memoir 2], ISSN 1634-0744                                                              
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