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Hornera humilis Busk, 1859
Family: HorneridaeGenus: Hornera
Colonies are small, erect and dichotomously branched. The branches are narrow, 0.6-0.8 mm in diameter, and do not anastomose. The encrusting base is about 1 mm in diameter and gives rise to three primary branches diverging at 120°, initiating a broad, cone-shaped colony. Branch surfaces immediately above the colony base are covered by cancelli and lack autozooidal apertures. Apertures of autozooids begin to appear further distally along the branches and always open on the outside of cone, with the cancelli-covered branch reverse surface oriented towards the interior of cone.
Autozooids have small, 0.05-0.08 mm diameter, subcircular apertures arranged in poorly defined longitudinal rows separated by low sinuous ridges, with about 6 rows across the width of a branch and a spacing of 0.21-0.34 mm between adjacent apertures longitudinally. Apertural spines and peristomes are lacking. Calcification between the apertures is smooth, without pustules.
Cancelli are distributed between autozooidal apertures on branch frontal surfaces. They are about 3-4 times more abundant than autozooids, and have circular to longitudinally elliptical openings. On branch reverse surfaces the cancelli are aligned in uniserial longitudinal rows separated by slightly raised areas of granular calcification.
Gonozooids are unknown.