Taxonomy
Seirocrinus subangularis is found in England, Germany, Canada and Japan.
Diagnostic description
- Stem pentagonal to circular with rounded interradii
- Symplectical areolae that are narrow elliptical to pyriform, widest at outer end, bordered by numerous small crenulae with highly rugose radial areas
- Cirri are weakly compressed with a rounded rhomboidal section
- Radials barely in contact or separated by basals
- Arms robust.Aboral ligament fossa of proximal brachials indistinctly L-shaped
- Syzsygies always absent
- Proximal pinnules incorporated in tegmen
- Seirocrinus with 7 secundibranchs, 4-11 inner tertibranchs, 13-17 outer tertibranchs and 11-19 post palmers
(After Simms 1989)