The Echinoid Directory

• Home
• Introduction
• Morphology
• Keys
• Classification
• 3D models
• Index to taxa
• Glossary
• Log in

Key to the genera of triplacidiids 1a. Ambulacra polygeminate; pore-pairs arranged into almost horizontal arcs. Eurypneustes 1b. Ambulacra trigeminate; pore-pairs not in horizontal arcs. Go to 2 2a. Single primary tubercle on both ambulacral and interambulacral plates. Gagaria 2a. Multiple equal primary tubercles on both ambulacral and interambulacral plates. Go to 3 3a. Wide interradial zone aborally with fine granules. Triplacidia 3b. No aboral zone of granules interradially. Mistechinus