View source for Enveloping canals

[[File:Fig 44.jpg|thumb|<font size="2">'''Fig. 1.'''  Enveloping canals produced by folded outer lamellas. '''A-D:''' Lamellae in the peripheral portion of three successive chambers. Stereograph, schematic, not to scale. '''A:''' ultimate and penultimate chamber: '''red:''' inner lamella; '''green:''' outer lamella of ultimate chamber, '''white:''' outer lamella of penultimate chamber. '''B:''' addition of the next chamber with an inner lamella in red and an outer lamella in blue. '''C:''' addition of an other chamber with its outer lamella in yellow. '''D:''' superposition of lamellas B and C over the then final chamber A after two additional growth steps. '''E:''' SEM micrograph of the complete test of ''Calcarina defrancii'' d'Orbigny, ventral view, showing distribution of canal orifices over all the test including the canaliferous spines. '''F:''' SEM micrograph of an epoxy resin cast of the shell cavities in ''Calcarina gaudichaudii'' d'Orbigny cut in a direction perpendicular to the axis of the spiral shell, ventral view; '''G:''' detailed SEM micrograph of the ventral shell surface of ''C. gaudichaudii''. Calcarinas from Keij Island, Indonesia. Recent. After Hottinger and Leutenegger, 1980. '''apil:''' axial pile of lamellae; '''ch:''' chamber and chamber lumen; '''co:''' canal orifice; '''csp:''' canaliferous spine; '''envc:''' enveloping canal; '''isc:''' intraseptal space or canal; '''il:''' [[inner lamella]]; '''lh:''' [[loop-hole]]; '''ol:''' [[outer lamella]]; '''p:''' [[pore]]; '''paf:''' perforate part of apertural face; '''ssk:''' supplemental skeleton; '''st:''' [[stolon]]; '''uc:''' umbilical canal network; '''uch:''' ultimate chamber suture, chamber walls broken off; (Hottinger, 2006; fig. 43)[http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]]

[[File:Fig 65.jpg|thumb|<font size="2">'''Fig. 2.''' Supplemental skeletons including marginal crests.
'''A-G:''' ''Pellatispira'' group ''provalei'' Yabe. '''H:''' ''P. fulgeria'' Whipple. Both species from Kalimantan, Borneo, Indonesia. Middle-Upper Eocene. '''I-J:''' ''Calcarina sp''., Kutei basin, Kalimantan. Pleistocene. '''A-D:''' SEM micrographs. '''G-J:''' transmitted light micrographs of oriented thin sections of free specimens. '''A:''' the free nepiont shows early spiral chambers not yet covered by a supplemental skeleton. An uncovered open interlocular space remains between the ultimate and penultimate chambers. '''B:''' detail of lateral view of a free nepiont revealing the early presence of canaliculate spines in the first volution of the spiral chambers and the modest extent of the marginal crest at this stage of growth. '''C:''' peripheral view of the margin of the second whorl. Note the strong radial spikes that support the thin imperforate walls of the marginal crest. '''D:''' septal face in oblique-peripheral view: the septal flap is reduced to a small area above the foramen. '''E:''' a lateral, flying cover of the interlocular space, with canal orifices at its margins, is produced by a free fold of an outer lamella and represents thus a primary element of the supplemental skeleton. '''F:''' in later growth stages, a first imperforate cover of the interlocular space may be bridged by supplementary chamberlets with a perforate, bilamellar wall. '''G:''' equatorial section. The primary bilamellar walls of the spiral chambers are coloured. All uncoloured constituents of the shell are part of the supplemental skeleton. '''H:''' Extreme development of the supplemental skeleton as a broad marginal crest covered with piles that are flanked by the canals of an enveloping system. '''I:''' the axial section of a trochospiral shell demonstrates the complex pattern of the umbilical cavities between umbilical piles of lamellae. The primary bilamellar walls of the spiral chambers are coloured. '''J:''' a section perpendicular to this axis of coiling shows that canalicular spines grow outward from the supplemental skeleton that envelops the primary bilamellar (coloured) wall of the spiral chambers.
Abbreviations: '''a:''' [[aperture]]; '''c:''' canals, canal orifices; '''ch:''' (spiral) chamber; '''chl:''' (supplemental) chamberlet; '''csp:''' canaliculate (pseudo)spine; '''f:''' [[foramen]]; '''is:''' intraseptal interlocular space; '''lh:''' [[loop-hole]]; '''mcr:''' [[marginal crest]]; '''p:''' [[pore]]; '''pil:''' [[pile]] (of [[lamellae]]); '''pr:''' [[proloculus]]; '''s:''' [[septum]]; '''schl:''' [[supplemental chamberlet]]; '''sf:''' [[septal flap]]; '''sk:''' [[supplemental skeleton]]; '''spi:''' [[spike]]; '''uc:''' umbilical cavity system; '''up:''' [[umbilical plate]]; (Hottinger, 2006; fig. 65 [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]]


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==Definition==
*''according to Hottinger (2006):''
'''ENVELOPING CANALS''' -  (intramural cavities, auct.); more or less tubular spaces parallel with the test surface formed within lateral chamber walls and communicating with intraseptal interlocular spaces. The enveloping canals are produced by (non-adhering) imperforate portions of outer lamellae, that also cover partly the intraseptal spaces and are fold into these spaces, leaving on both sides of this "flying cover" alternating rows of openings for ectoplasmic flow over grooves in the perforate wall, situated between imperforate inflational ridges (feathering).







==References==
Hottinger L. & Leutenegger S. (1980), The structure of calcarinid Foraminifera.- Schweizerische Paläontologische Abhandlungen, Basel, N° 101, p. 115-151.

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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