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Acrosphaera spinosa echinoides Haeckel, 1887

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Acrosphaera echinoides
Shell a regular sphere, covered with numerous, straight, radial spines, irregularly scattered over the whole surface. In the half meridian of the shell twenty to thirty irregular roundish pores of variable size, one to four times as broad as the bars. Spines conical, strong, quite radial, at the top of small conical elevations, which are perforated by from three to six pores.
Dimensions.-Diameter of the shell 0.12 to 0.15, of the pores 0.002 to 0.008; length of the spines 0.015, of their basal zones 0.01.
Habitat.-South-east corner of the Pacific, Valparaiso, Station 298, surface.
Haeckel 1887

Lattice shell thick-walled, approximately spherical, 118-200µm in maximum diameter, slightly convolute with numerous small protuberances and alternating depressions. Protuberances 15-20µm in diameter; densely perforated by large, irregular, subangular pores 8-22µm in diameter. Simple spines 10-90µm long project from summit of each protuberance. Intervening depressions of lattice shell broad, sparsely perforated by small round pores 3-10µm in diameter.

Our detailed observations of this species have been confined to the Lower and Middle Miocene recovery of Site 55, 63 and 77. Acrosphaera spinosa echinoides undergoes a pronounced size dercrease in the Upper Miocene at Site 77, and persists in variable frequencies to the Lower Pliocene. The transition from A. s. echinoides to A. s. spinosa is complex and will require additional study.
Bjørklund 1979











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