View source for Tunnel

[[File:Fig 31.jpg|thumb|<font size="2">'''Fig. 1.''' Chomata. '''A-C:''' ''Eowedekindellina sp.'' Permian, Iran, Allemann collection, oblique, subaxial and subequatorial sections, transmitted light micrographs, and model. Note poleward extension of chomata forming a basal layer. '''D-F:''' ordinary chomata in ''Triticites sp.'', equatorial and axial sections, transmitted light micrographs and model. Lower Permian, Spitzbergen. Note in D the sector-wise appearance and disappearance of the chomata due to the slight obliquity of the section.
'''ath:''' antetheca; '''c:''' choma; '''c*:''' cutoff choma stressing the uncertainty about the connection between the choma and the antetheca; '''fl:''' fluted septa; '''kth:''' keriotheca; '''s:''' septum; '''sp:''' septal pores; '''spth:''' spirotheca; '''t:''' tunnel; (Hottinger, 2006; fig. 31 [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]]

[[File:Fig.32A-D.png|thumb|<font size="2">'''Fig. 2.''' Columellas. Transmitted light micrographs.
'''A-D:''' ''Kurnubia palastiniensis'' Henson. Upper Jurassic, Northeastern Morocco. '''A:''' transverse section near and almost parallel to the axis of coiling; '''B:''' axial section; '''C-D:''' oblique sections. Position of sections relative to the axial section marked by red lines; '''b:''' [[beam]]; '''col:''' [[columella]];  '''r:''' [[rafter]]; '''s:''' [[septum]]; '''sl:''' [[septulum]]; '''t:''' [[tunnel]]; '''wsut:''' whorl suture; (Hottinger, 2006; fig. 32; [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]]

[[File:Fig 66.jpg|thumb|<font size="2">'''Fig. 3.''' Septal and chomatal "pores" in ''Triticites plummeri'', Graham Fm., Texas, Permian. Transmitted light micrographs. '''A:''' subaxial section; '''B:''' details in equatorial section. Both pore-like features have nothing in common with true pores. Septal pores are tiny multiple foramina. The nature of chomatal pores, a wall texture particular to fusulinids, is not understood at present. '''c:''' [[choma]]; '''c*p:''' chomatal "pores"; '''kth:''' [[keriotheka]]; '''sp:''' septal "pores". '''t:''' [[tunnel]]; '''te:''' [[tectum]]; (Hottinger, 2006; fig. 66 [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]]

__FORCETOC__
==Definition==
*''according to Hottinger (2006):''
'''TUNNEL''' - an intercameral foramen in an interiomarginal-basal position bordered by endoskeletal structures narrowing the communication between the open [[chamber lumen]] and the spiral space extending through the successive tunnel foramina. The tunnel is produced by resorption of parts of an [[apertural face]] and/or of an apertural [[mask]]. May be multiplied to form a single row of basal foramina in fusiform shells. 


''Remarks'': Introduced originally for fusulinids, where the tunnel is bordered by chomata and may be multiplied - together with the endoskeletal elements, the [[parachomata]] - the term has been extended to pfenderinids (Hottinger, 1978). In this family the tunnel is bordered by being incised in a columellar [[endoskeleton]] and may be multiplied as multiple, parallel incisions in such complex genera as ''Sanderella''. In addition, the term is extended here to nummulitids where the tunnel is bordered by a pair of umbilical plates in much the same position as the chomata in fusulinids. In nummulitids, no multiplication of tunnels has been observed so far.

==See also==
*[[apertural face]]
*[[chamber lumen]]
*[[endoskeleton]]
*[[foramen]]
*[[mask]]
*[[umbilical plate]]








==References==
Hottinger (1978), Comparative anatomy of elementary shell structures in selected larger Foraminifera. In: Hedley R.H. & Adams C.G. (eds.), Foraminifera, Volume 3, Academic Press, London, p. 203-266.

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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