 |
 |
 |
| Chalk Group | Malacostracans | Cirripedes |
 |
 |
 |
| Asteroids | Ophiuroids | Crinoids |
|
TERMINOLOGY |
|
|
|
|
| Chalk Group | Malacostracans | Cirripedes |
|
|
|
|
| Asteroids | Ophiuroids | Crinoids |
 |
 |
 |
| Irregular Echinoids | Regular Echinoids | Echinoid Spines |