Cribrilina watersi Andersson, 1902
Colonies are encrusting, multiserial, sheet-like, unilamellar or rarely bifoliate due to back-to-back growth. Each autozooid has 8-10 distolateral pore chambers which may be visible in abraded colonies and at growing edges. The ancestrula has a costate frontal shield.
Autozooids are moderately small, 0.38-0.60 mm long by 0.28-0.42 mm wide, and roughly rhombic in outline shape. The gymnocyst is normally not visible. The gently convex frontal shield is formed by 5-13 costae (including the apertural bar), most often 7-11, linked by stout lateral costal fusions and united at the centre of the frontal shield. There are 1-4 intercostal pores and each costa has 0-2 lumen pores placed haphazardly. The apertural bar is very stout with a variably developed median mucro having one or two lumen pores on its proximal side. The sunken orifice is D-shaped, broader than long, with one median, flattened oral spine in non-ovicellate zooids but no spines in ovicellate zooids. Ovicells are small, short and have a single, inverted T-shaped or several smaller proximal windows in the ectooecium.
Avicularia are adventitious, paired on either side of the orifice, directed distolaterally, with a short triangular rostrum, raised at its distal end, a rounded proximal end, and an uncalcified pivotal bar.
Of the five species of Cribrilina recorded from the East Anglian Crags (Bishop 1994), this species is most easily distinguished by its very stout apertural bar and the short ovicell containing one or several uncalcified windows in the ectooecium.
Pliocene, Late Zanclean–Early Piacenzian, Coralline Crag Formation, Aldeburgh (including Crag Pit Nursery), Sudbourne and Sutton. Pliocene, Red Crag Formation, Walton-on-the-Naze, Essex, Waldringfield, Suffolk. Also recorded by Bishop (1994, pp. 235-6) from the Luchtbal Sands of Wilmarsdonk, Belgium and the Recent of East Greenland.