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Cycladophora bicornis helios Lombari and Lazarus, 1988

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Medium hemisphaerical cephalis with scattered small circular pores, 2 medium length three-bladed apical horns. Short conical upper thorax with small irregularly distributed subcircular pores. Lower thorax is compressed, widely flared, inflated. The transition between upper and lower thorax is smoothly curved. The lower thorax pores are medium to large, elliptic/circular to sub-hexagonal, while the bars are of medium width, thin, and smoothly rounded. The base of the thorax is marked by an internal septum. A very short abdominal fringe with one to two rows of pores is characteristic of the species. This abdominal segment is nearly horizontal, and the outer row of pores is usually incomplete, producing in many specimens a ring of radiating narrow triangular teeth. Several specimens were seen with a nearly complete basal plate, which was very thin walled, and with widely spaced, irregularly distributed large irregularly shaped pores.

Type: DSDP Site 173-20-CC. England finder number Z27/3.

This subspecies has only been seen in the late Miocene of the North Pacific and may be useful for late Miocene stratigraphy. In 173-19-CC, a morphologic variant of this species is seen with larger pores and a flat conical shell outline. C. b. helios can be distinguished from C. b.bicornis by the characters of the lower thorax (text-fig. 9) and by its well-developed basal teeth.

Occurrence: DSDP Site 173. cores 15 through 20 (late Miocene). It is generally few in abundance.
Lombari and Lazarus 1988











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