Cyrtolites

Classification
Phylum: Mollusca
Class: Tergomya
Order: Cyrtonellida
Family: Cyrtolitidae
Genus: Cyrtolites Conrad, 1838
Cincinnatian Species: Cyrtolites ornatus

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Alternate spelling: Bellerphon (Cyrtolites)
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Geologic Range
Middle Ordovician – Early Silurian

Common Paleoecology
Cyrtolites is an extinct genus of slow-moving low-level epifaunal grazers

Identification in Hand Sample:

Loosely coiled shell
Anterior lip with shallow, angular sinus
Aperture is quadrate
2 to 3 gradually enlarging volutions
Without septa

Geographic Occurrences

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Fossils of Ohio (1996):

Loosely coiled shell

Treatise on Invertebrate Paleontology, Part I, Vol. 1 (1960):

Anterior lip with somewhat shallow, angular sinus, aperture quadrate, whorls barely in contact or possibly disjunct in some species; with sharp median carina and pair of lateral ridges; umilici widely open; ornament wide collabral undulations and fine cancellating threads.

McFarlan (1931):

Volutions 2 or 3, gradually enlarging, scarcely contiguous. Carinated on the back, often on the sides, giving subquadrate cross section. Aperture with or without median notch in outer lip, no slit band. Shell without callosities. Surface reticulated or cancellated.

Ulrich & Scofield (1897):

Shell coiled in the same plane, symmetrically or nearly so; volutions two or three, scarcely contiguous, the last occasionally free, enlarging gradually, carinated on the back and often on the sides, giving a subquadrate cross section; aperture not abruptly expanding, with or without a median notch in the outer lip; no slit-band; shell thin, without callosities of any kind; surface sculpture reticulated or cancellated, consisting of straight or obliquely curved regular transverse lines connected by short oblique lines.

Conrad (1838):

Shell Inflated, volutions few, increasing rapidly in size; transversely ovate; destitute of septa (117-118).

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