The Echinoid Directory

• Test small (less than 10 mm diameter), circular in outline. Test plating rigid.
• Apical disc very small, approximately 25% diameter of test, and much smaller than the peristome. Ocular plates exsert and projecting far beyond the genital plates. Apical disc firmly bound to corona. Five gonopores.
• Ambulacra narrow and almost straight; composed of simple, pentagonal plates throughout. Single tubercle to each element.
• Pore-pairs small and non-conjugate; uniserial.
• Interambulacral zones wide with about 6 pentagonal plates in a column.
• Single large primary tubercle dominates each interambulacral plate; mamelon very large and imperforate; no platform; mamelons largest at ambitus and decreasing adapically.
• Scrobicular circle of tubercles partially developed; interradial zone with narrow band of granules.
• Peristome large, circular; no buccal notches.
• Interior of peristome not seen.

Late Triassic; Peru and western Canada.

Parvicidaris microapicalis Smith, 1994, p. 195, by original designation. Holotype; Smithsonian Institution, Washington USNM465266.

• Only the type species.

?Euechinoidea stem group, Triadocidaridae.

Monotypic.

Very small tests but apparently adult, since gonopores are large and fully open. Distinguished from Mikrocidaris by having ocular plates apparently still in contact with the ring of genital plates, and by its imperforate tubercles.

Smith, A. B. 1994. Triassic echinoids from Peru. Palaeontographica A 233, 177-202.