Hallopora andrewsi

Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Halloporidae
Genus: Hallopora
Species: Hallopora andrewsi (Nicholson, 1874)

Taxonomic Details

Taxonomic History (Nickles & Bassler, 1900; Under Callopora andrewsi)

  • 1874 Chaetetes pulchellus (not of Milne-Edwards & Haime) Nicholson, Quar. Jour. Geol. Soc. London, XXX, p. 503, pl. xxix, 5-5b.
  • 1875 Chaetetes pulchellus (not of Milne-Edwards & Haime) Nicholson, Pal. Ohio, II, p. 195, pl. xxi, 5, 5a.
  • 1881 Monticulipora (Heterotrypa) andrewsi Nicholson, Genus Monticulipora, p. 128, fig. 21, pl. v, 1, 1a.
  • 1882 Callopora andrewsi Ulrich, Jour. Cincinnati Soc. Nat. Hist., V, p. 252.
  • 1883 Monticulipora andrewsii (Van Cleve) Hall, Twelfth Ann. Rep. Indiana Geo. Nat. Hist., p. 249, pl. xi, 9.
  • 1888 Monticulipora andrewsii James and James, Jour. Cincinnati Soc. Nat., Hist., X, p. 178.
  • 1894 Monticulipora andrewsii J.F. James, Jour. Cincinnati Soc. Nat. Hist., XVI, p. 200.

Note: Probably all species referred to as Hallopora from the type Cincinnatian are actually Parvohallopora. (Steven Holland, UGA Strat Lab 2013)

Stratigraphic Occurrences


Geographic Occurrences

Map point data provided by iDigBio.

Stratigraphic Description

Sequences (Formations)

  • C3 Sequence (Corryville)
  • C2 Sequence (Bellevue)

Identification in Hand Sample

  • Zoarium Morphology: Ramose; 6-12 mm
  • Zoecia: 7 in 2mm; surrounded by variable number of mesopores
  • Mesozooids: Numerous
  • Monticules: Low and rounded
  • Maculae: Composed of larger apertures, with more numerous mesopores

Hallopora andrewsi from the McMillan Formation of Georgetown, Ohio (OUIP 876)

Published Description

McFarlan (1931)

  • Zooarium ramose, 6-12 mm in diameter. Surface typically with low, rounded monticules composed of larger apertures and more numerous mesopores. Zooecia 7 in 2 mm, surrounded by a variable number of angular or subcircular mesopores. Tabulations of zooecia variable.

Cumings (1907):

  • “Corallum variable in form, usually of subcylindrical branches, which have a diameter of from 2 to 6 lines, sometimes forming flattened and expanded subpalmate fronds, sometimes inosculating. Corallites thin-walled, polygonal, unequal in size, about eight of the average ones occupying the space of 1 line. Surface exhibiting rounded or somewhat stellate groups of larger corallites, of which two or three occupy the space half a line, and which sometimes have very minute intermediate tubuli between them. These groups of larger corallites generally comprise from five to seven individuals, and they are placed about 1 line apart; they are very slightly or not at all elevated above the general surface so that there are no conspicuous tubercles.
  • “The characters of this species are so well marked as to render its recognition very easy, even in small fragments.” – Nicholson, loc. cit.
  • Internally this species exhibits very beautifully the peculiar structure of the genus Callopora. Toward the surface, the walls are much thickened and ring-like and are separated from each other by a set of small rounded mesopores. In longitudinal sections, the zooecia and mesopores are seen to be crossed by a well-developed series of straight diaphragms, which are very close together in the mesopores.