Bythopora arctipora

• Zoarium Morphology: Ramose; usually slender, but sometimes larger
• Zoecia: Oblique apertures, narrowing above; acanthopores strong, usually one per zooecia (never numerous)
• Mesozooids: Few
• Monticules: Smooth
• Maculae: N/A

• Genus: Zooarium of smooth, slender branches, with small oblique zooecia, the apertures narrowing above and with channeled interspace. Mesopores few. Acanthopores never numerous.
• Above is the same description given for the genus. B. arctipora is characterized by its delicate zooaria, being more slender and ramose (1-2mm diameter branches).

Cumings (1907):

• “Polyzoary forming a cylindrical, slightly branched frond, which is not sharp-edged, exhibits no non-celluliferous borders and shows no traces of a central laminar axis. Cells arranged in obscurely longitudinal alternating rows, apparently perpendicular to the surface, and radiating in all directions from an imaginary axis. Cell-mouths very much compressed, much long than wide, expanded below and attenuated superiorly, where they are often much twisted and bent. Upon the whole, the cells are pyriform in shape, with their narrow ends directed upwards, about eight occupying the space of one line measured vertically, and twelve the same space measured diagonally. The cells are not always in contact, especially in their upper portion; and their borders are always distinctly marked off by impressed lines; but they are not arranged between elevated longitudinal ridges. The margins of the cells are very thick and conspicuous, not granulated, tuberculated, or spinigerous.”
• “The best-preserved fragment examined had a length of eight and a half lines, dividing at its summit into two branches, its diameter being rather more than one-third of a line.”
• “From its cylindrical form, and the absence of a laminar axis or of non-poriferous margins, it would seem certain that this singular form is not a Ptilodictya; but I am at a loss to know where it should properly be placed, its extreme minuteness rendering its generic affinities very uncertain, owing to the impossibility of making out the details of its internal structure. It has, however, some affinity with Ptilodictya (?) raripora, Hall, from the Clinton Group, and I have therefore referred it provisionally to this genus” – Nicholson, loc. cit.

Nickles & Bassler (1900)

• Bythopora Miller and Dyer: Zoarium ramose, branches usually slender, sometimes of considerable size; zoecia practically without diaphragms; apertures oblique, narrowing above; interspaces caniculate; mesopores few; acanthopores comparatively strong, rarely more than one to each zooecium, sometimes wanting.

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