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Buryella tetradica
Foreman, 1973
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Description - Add description
Description: Shell of four segments subovate, smooth, with none of the strictures expressed externally. Cephalis subspherical, with a few circular pores, bearing a short, sharp horn or thorn. Collar stricture with four collar pores internally, and vertical pore expressed as a short horizontally directed tube. Thorax conical, with circular pores arranged in approximately three vague transverse rows or more irregular. Third segment largest, inflated, with greatest dimension medianly or in the distal half. Uniform circular pores are arranged in longitudinal and four to five transverse rows. Area between the longitudinal rows raised. Last segment inverted truncate-conical, with a smooth thinner wall and two to seven transverse rows of circular to elliptical pores. Distal margin scalloped or even, without a differentiated rim.
Measurements (based on twenty specimens from Cores 86-8, 96-3,
94-32, 94-31, and 94-30). Length overall, exclusive of horn, 120-
185μ, length of cephalis and thorax 35-45μ, of third segment 40-
65μ, of last segment 70-95μ; greatest width 70-95μ.
Remarks: The thorax of B. tetradica is considered homologous with the two postcephalic segments of B. pentadica. This difference in the number of segments between the cephalis and the large inflated segment serves to distinguish these two closely related species (B. pentadica,
ancestor and B. tetradica, descendant). B. tetradica differs from its descendant B. clinata by having pores of the third segment in transverse and longitudinal rows. | | Foreman 1973 | Description: Fusiform test of four segments with smooth outline. Cephalis spheroidal, sparsely perforate with short apical horn and distinct vertical pore directly above indistinct collar stricture. Thorax inflated conical, with circular pores loosely quincuncial in three rows. Third segment largest, inflated medially, pores in 4-6 transverse rows; pores also longitudinally aligned. Final segment thinner, inverted truncate-conical, with circular to elliptical pores arranged in 2-7 transverse rows. Remarks: Longitudinal alignment of abdominal pores and transverse alignment in some specimens is poorly developed in early forms of this species.
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