Streptelasma is an extinct genus of solitary stationary epifaunal suspension feeders
Identification in Hand Sample:
- Curved corallum
- Corrallum funnel-shaped, deep calice
- No dissepiments
- Corallum solitary
- Streptelasma Hall is a solitary rugose coral that characteristically has a curved corallum. The corallum has a funnel-shaped, deep calice. Septa are numerous. Major septa are fused into a weak axial structure in early stages; minor speta are short. A fossula is present in some species. Tabulae may be present. Dissepiments are absent. The epitheca is thin. Streptelasma is found in Ordovician and Silurian strata in Ohio. Ordovician representatives are commonly small, encrusting forms.
- Minor septa are all short
- From my experience with of the Scandinavian and other species of Streptelasma, the only fossular structures of characteristic of this genus are either a pdeudofossula (without tabular depression) or a septofossula (defined by Neuman 1984, pp. 122-123 and fig. 2F as a fossular pit in the bottom of the calice shaped by a considerably shortened cardinal septum in the last precalicular ontogenetic stage). The incomplete tabulae in the type species, Streptelasma corniculum Hall, 1847 (for description see Neuman 1969, pp. 10-11, figs. 4-6), and in all Scandinavian species (Neuman 1969, 1977) are not of tabelloid type (comparable to elongated dissepiments). The incomplete tabulae in the periphery of the corallite which butress the complete tabulae are defined by Neuman (1969, p. 6, fig. 2D) as complementary plates.
Treatise on Invertebrate Paleontology, Part F, 1 of 2 (1981):
- Corallum solitary; trochoid , ceratoid, or cylindrical, wit convex cardinal side , cardinal fossula open; major septa in early stages long, thin or moderately thick, normally fused into weak axial structure, in late stages thin, somewhat withdrawn from axis, and not forming axial structure, axial edges of major septa transversely corrugated and with sparse vermiform lobes; minor septa rudimentary or short; peripheral stereozone present in all stages; tabulae complete, convex, with wide axial depression and mostly with lateral tabulae; no dissepiments.