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Stylotrochus (Stylotrochiscus) sol Campbell and Clark , 1944

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Stylotrochus (Stylotrochiscus) sol n.sp. Campbell and Clark 1944 p. 28; pl. 4, fig 7,9-11

Shell commonly very large (largest species in this collection), circular, coin-shaped. Flat on two broad faces, and with numerous (at least 40, sometimes 60) piercing radial spines, these spines hyaline needles, short (25.4-34.2 μ), sharply pointed, straight or bent, and freely scattered around circumference; in addition, they are continued internally and with side-branches at various intervals, and supplementary marginal spinules are scattered in interradii which are prolongations of spongy framework; spongy framework irregular, without concentric rings or spiral structure, generally thin and frothy; pores subcircular to subelliptical, rarely fused in pairs, of several sizes freely scattered, generally closely and deeply set. Diameter, upward to 410 μ, of pores, 2.2-10 μ.
Stylotrochus sol n.sp. differs from helianthus (Haeckel, 1887) in its much greater diameter (almost twice as great at maximum) and in shorter radial spines. Other described species have a much smaller number of radial spines or have concentric structures. One of largest, most abundant species in this collection. Nearly every sample contains a great many specimens. Species probably one of most successful of Spumellaria in this material, and, indeed, these foamy species are almost always most abundant everywhere, as in Eocene, and in recent Pacific.

Picture: plate 4 (7, 9-11) Stylotrochus (Stylotrochiscus) sol n.sp. U.C.M.Pal. loc. A 3464, A 3467, A 3468, A 3469
Campbell and Clark 1944











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