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Calocyclas talwanii Bjørklund and Kellogg, 1972

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Shell divided into three segments, thick-walled, rough-surfaced. Cephalis small, spherical to subspherical, bearing a long, robust, slightly curved apical spine with a finely papillate surface. Cephalis pores very small, circular, deep-set. Collar stricture indistinct. Thorax campanulate, bearing large, circular pores deeply set in hexagonal frames. In the better-preserved specimens, the thoracic pores contain a delicate meshwork of intricate design, and a thin dorsal spine projects from the thorax. Lumbar stricture a distinct ring bearing a number of vertical channels where pores extend across it. Abdomen bearing large, deep-set, circular to elliptical pores which may also contain a siliceous network similar to that of the thoracic pores; tapering toward the open mouth.
Dimensions of holotype: Width of thorax at widest point 186 microns. Length of cephalis and thorax 157 microns. Length of apical horn 143 microns. Width at lumbar stricture 186 microns. Width of abdomen at mouth 129 microns. Diameter of largest thoracic pores 21 microns. Diameter of largest abdominal pores 21 microns.
Calocyclas talwanii may be distinguished from other members of its genus by its large size, rough surface, the papillate surface of its long, curved apical horn, and the distinctive meshwork in its thoracic and abdominal pores.
Bjørklund and Kellogg 1972











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