Title: Arrangement of chambers Cont'
1Lecture 5
Arrangement of chambers(Cont.)
2- Milioline Winding growth with two chambers to
the whorl with the aperture alternately at one
end and then at the other. The successive
chambers are added at 144º to each other
(quinqueloculine), 120º (triloculine) or 180º
(biloculine).
Pyrgo
Quinqueloculina
Triloculina
Spiroloculina
3- Polymorphine The successive chambers spiral
about the growth axis of the test, all the
apertures pointing in the same direction.
Globulina gibba
Polymorphina
Guttulina
4- Mixed chamber arrangement
- Mixed or multiform growth, where the juvenile is
different in arrangement from the adult chambers,
is common and in some cases three different modes
may be shown. - -Planispiral to uncoiled uniserial, Astacolus.
- -Planispiral to biserial, Spiroplectammina.
- -Biserial to uniserial, Bigenerina.
- -Trochospiral to triserial, Eggerella.
5- -Triserial to biserial, Gaudryina.
- -Triserial to uniserial, Clavulina.
- -Trochospiral to annular conical, Patellina.
- -Planispiral to annular discoid, Archians.
- -Trochospiral or planispiral to annular complex,
Orbitoides.
6Morphology of chambers and the aperture
- Chambers are spherical to flattened in shape.
- They are separated from each other by partitions
(or septa) the suture of which are rectilinear,
curved or winding. - The last chamber communicates with the exterior
through an aperture. - The aperture may be simple, in this case taking
the shape of a circle, a slit or a crescent or
it may be radial or denderitic, sometimes at the
top of a neck or partially covered by calcareous
projections (tooth, valve, trematophore or
tegillum). - There may also be multiple apertures with several
small orifices arranged in a raw (linear
aperture) or randomly (cribrate aperture). Its
position in relation to the chamber may be basal,
terminal, sutural or peripheral.
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8- The shape of the aperture may be
- Rounded
- Fissurine (elliptical)
- Toothed (simple or bifid)
- Straight slit
- Arched slit
- Denderitic
- Phialine
- Radiate
- Cribrate
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11- The position of the aperture may be
- Terminal
- Subterminal
- Sutural (textularian)
- Areal
- Umbilical
- Interiomarginal
- Exteriomarginal
- Equatorial
- On the apertural face
- At the end of the tube
- Some modifications of the aperture
- Simple lip
- Crenulated lips
- Lateral flanges
- Apertural teeth
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14Surface ornamentation,
- The surface of the test is it smooth or covered
with striations, ribs, tubercules, spines, etc. - The extranal surface of the test may bear spines
(termed spinose), keels (carinate), rugae
(rugose), fine striae (striate), coarse costae
(costate), granules (granulate), or a reticulate
sculpture. - These features should be used with caution in
distinguishing certain genera and species for
they vary through ontogeny and with environment.
15The surface ornamentation of the test may
be -Costae, Ribs, striations. -Hispid (very fine
short and hair-like spines). -Spinose (provided
with very fine spines, generally
elongate). -Rugose (characterized by rough
ornamentation which may form ridges). -Nodose
(surface ornamented with small knobs). -Reticulate
(with a honey-comb like surface). -Beaded
(provided with ornamentation like a string of
beads). -Pitted (small, generally rounded
depressions in the surface of the wal. -Limbated
(bordered by or provided with a flat or raised
strip). -Keeled (marginal cord of the
periphery). -Carinae (the edges of the chambers
often bear projecting sharp keels). -Septal
bridges (retral processes). -Smooth.
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18Sutures
- They are simple or limbate (underlined by a band
of variable width). - The sutures are of two types
- -Spiral suture division between different whorls
of the test. - -Intercameral suture division between the
chambers themselves. - It may be described as
- Depressed, Flush, raised, limbate and obscured by
the cortex. - Or may be
- Straight, arched or curved, grooved and
reticulate.
19Periphery
- Periphery of the test is the outer margin of the
test, termed as the axial periphery (as shown in
the axial or periphery view) and the equatorial
periphery (as shown in ventral or dorsal view). - The axial periphery may be desribed as
- Rounded
- Acute
- Keeled (ridge-like thickening of the chamber
wall, present on the periphery of the test. - The equatorial periphery may be described as
- Lobulate
- Nonlobulate
20Umbilicus
Umbilicus is it vacant or occupied by one or
more granules. It is a central area where the
septal traces (sutures) meet. When the umbilicus
is completely filled with secondary material, it
is called umbo. If slightly filled, it is called
an umbilical plug. The test may be described
as Umbilicate test (with an umbilicus). -Monoumbi
licate as in Globigerina -Biumbilicate as in
Hantkenina and Hastigerina. Umbonate test (with
an umbo) Monoumbonate as in Rotalia
StreblusAmmonia Biumbonate as in Robolus
Elphidium
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