Homotrypa obliqua

Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Mesotrypidae
Genus: Homotrypa
Species: Homotrypa obliqua (Ulrich, 1882)

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Taxonomic History (Nickles & Bassler, 1900)

  • 1882 Homotrypa obliqua Ulrich, Jour. Cincinnati Soc. Nat. Hist., V, p. 243, pl. x, 6, 6b.
  • 1889 Homotrypa obliqua Miller, North American Geol. Pal., fig. 489 (p. 310).
  • 1896 Homotrypa obliqua J.F. James, Jour. Cincinnati Soc. Nat. Hist., XVIII, p. 124.

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Stratigraphic Occurrences


Geographic Occurrences

Map point data provided by iDigBio.
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Sequences (Formations)

  • C3 Sequence (Corryville)
  • C2 Sequence (Fairview: Fairmount)

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Identification in Hand Sample

  • Zoarium Morphology: Ramose to frondose
  • Zoecia: Often oblique; thin walled (sometimes crenulated);
  • Mesozooids: Few, generally clustered
  • Monticules: n/a
  • Maculae: Characteristic: larger cell apertures
Homotrypa obliqua

Homotrypa obliqua from McMillan Formation of Hamilton County, Ohio (CMCIP 27769)

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Davis (1998)

  • Shape variable, from cylindrical to fan-like. Apertures enlarged in maculae

Bassler (1903)

  • This abundant Lorraine species in its internal characters is very much like H curvata. The absence of diaphragms and the slightly crinkled walls in the axial region distinguish it from H. curvata. Externally, however, the two species are readily separated by their different methods of growth, the ramose zoarium of H. obliqua with its cylindrical or slightly compressed, more or less tuberculated, branches being quite characteristic. In the fairmount beds of the Cincinnati area a form of the species with strongly tuberculated, cylindrical branches seldom over 5 or 6 mm. in diameter, occurs very abundantly. The succeeding Bellevue beds also hold the species in abundance, but here the zoarium is more robust and the branches are often subcylindrical and nearly smooth. Specimens 6 cm. or more in length without dividing and 15 mm. in diameter are often found. The prevailing form of zoarium in the Corryvile beds is a rather broad, somewhat compressed, tuberculated branch, and specimens of this kind probably led Nicholson to identify H. dawsoni at Cincinnati. The internal structure of these various forms of the species is essentially the same. About 10 zooecia in 3 mm.
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