The Echinoid Directory

• Test globular; plating thin and imbricate.
• Apical disc small, with single large genital plate.
• Ambulacra narrow; biserial; plating imbricate. Pore-pairs perradial and with the inner pore larger and sutural, forming a notch on the adoral plate margin.
• Large adradial extensions of the ambulacral plates extend beneath adjacent interambulacral plates. Radial water vessel enclosed by perradial flanges.
• Interambulacral zones wider than ambulacral zones; composed of numerous small scale-like plates irregularly arranged.
• No primary tubercles, but all plates apparently covered in small granules.
• Lantern present; teeth wide and flattened and composed of a double series of elements that give the tooth a V-shaped pattern.

Upper Ordovician (Ashgill), Scotland.

Ectinechinus lamonti MacBride & Spencer, 1938, by original designation.

• Only the type species.

Stem group Echinoidea; unnamed plesion.

Monotypic; Subjective junior synonym of Aulechinus Bather & Spencer, 1934.

Aulechinus is morphologically very similar, but was distinguished by having an external perradial groove and single pores piercing ambulacral plates. The latter does not seem to be true, and the former feature may be taphonomic in origin. Consequently, there seems little reason to maintain the two genera.

MacBride, E. W. & Spencer, W. K. 1938. Two new Echinoidea, Aulechinus and Ectinechinus, and an adult plated holothurian, Eothuria, from the Upper Ordovician of Girvan, Scotland. Transactions of the Royal Society, London B229, 91-136, pls 10-17.