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Tholospyris infericosta
Goll, 1969
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Description - Add description
THOLOSPYRIS INFERICOSTA n. sp. Goll 1969 p. 326; pl. 55, fig. 7, 10-12
Sagittal ring subpolygonal; 51 to 74 μ. high; 37 to 55 μ thick; joined directly to front and back of lattice shell. Frontal spine short; vertical spine very short, projecting from lower third of sagittal ring; no apical or axial spines. A single connector bar projects vertically from front-apex of sagittal ring; primary lateral bars joined to basal ring; no other connector bars.
Basal ring oval, indented laterally and sagittally; 55 to 75 μ wide; 37 to 50 μ thick; joined directly to front and back of sagittal ring; encloses four basal pores; narrow horizontal rib extends around circumference. Two to six sulcate lattice bars project downward from back of basal ring and connect distally to horizontal lattice bar or ribbon of lattice shell that is joined to lateral portions of basal ring. Short sulcate lattice spines project downward from this horizontal process; in some specimens two to four sulcate, laterally projecting basal spines are joined to lateral extremes of basal ring. Lattice shell 138 to 184 μ high; 92 to 134 μ wide: slightly constricted sagittally; surrounds apex of sagittal ring; has appearance of thin sheet perforated by circular widely spaced lattice pores 2 to 32μ in diameter. In some specimens lattice bars have narrow median rib on outer surface. Four lattice bars joined to sagittal ring; one junction at proximal end of apical connector bar; one junction between apical connector bar and frontal spine; two junctions between apical connector bar and vertical spine, fhree to seven short, sulcate lattice spines project from apical portion of lattice shell. No vertical, sternal, or frontal pores.
Diagnosis:
A species of Tholospyris characterized by a lattice shell that surrounds the apex of the sagittal ring and extends below the back of the tribladed basal ring.
Remarks:
Representatives of Tholospyris infericosta, n. sp., differ from those of T. kantiana in having a tribladcd basal ring; from those of T. proccra, n. sp., in having primary-lateral bars; and from those of T. scaphipes in having a lattice shell that surrounds the apex of the sagittal ring. Skeletons of the type-species of Tholospyris, T. cortinisca, have three basal spines, and the lattice shell does not extend below the basal ring.
Occurrence:
Representatives of Tholospyris infericosta are in all the samples between MSN 132P. 90-92 cm. (middle Miocene) and AMPH 102P, 50-52 cm. (upper Miocene), and in MSN 143P, 890-892 cm. (middle Pliocene).
Holotxpc:
USNM 650344, from core sample AMPH 102P, 482-484 cm. (upper Miocene).
Picture: 7, 10-12 - Tholospyris infericosta Goll, n. sp. Basal, front, left-sied, and back views, respectively of holotype; USNM650344, core sample AMPH 102P, 482-484 cm. | | Goll 1969 |
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