The Echinoid Directory

• Test possibly spherical in life and large (ca. 120-150 mm diameter).
• Apical disc unknown.
• Ambulacra more or less straight and narrow; biserial. Plating simple with slightly elongate pore-pair on each plate. Tuberculation in central zone too worn to be sure of pattern.
• Adradial margins of ambulacral plates bevelled strongly beneath interambulacral plates. On the inner surface of ambulacral plates there are strongly developed perradially directed flanges that fully enclose the radial water vessel within the ambulacral plates.
• Interambulacral zones wide; composed of apparently irregularly arranged and sized plates, although this is almost certainly greatly exaggerated by preservation. Plates imbricate towards the interradius where there is a row of small plates that lie on top of their neighbours on either side.
• All large interambulacral plates bear a single imperforate and non-crenulate primary tubercle. This is surrounded by a small circle of scrobicular tubercles. Smaller subrounded plates occur in amongst the larger tubercle-bearing plates.
• Peristome, lantern and spines all unknown.

Upper Devonian, Alberta, Canada.

Albertechinus montanus Stearn, 1956, p. 744, by original designation. Holotype, Geological Survey of Canada, Ottawa 12770.

• A. montanus Stearn 1956; Upper Devonian, Canada
• A. thomasi (Stainbrook, 1920);
• A. wanneri (Browne, 1967); Middle Devonian, Australia

Stem group Echinoidea; Archaeocidaridae.

Monotypic.

The genus is distinguished from Lepidocidaris by its biserial ambulacra and by the rather heterogeneous size and shape of its interambulacral plates.

Stearn, C. W. 1956. A new echinoid from the Upper Devonian of Alberta. Journal of Paleontology 30, 741-746, pl. 81.