{ More recent Sea { 15. Autechinida with | 15. Desmosticha { Urchins (with 20 { band-like ambulacra | { rows of plates) { 16. Autechnidia with | 16. Petalosticha { _Autechinida_ { leaf-like ambulacra | | { VIII. { 17. Eupodia with scuti- | 17. Aspidochirota { Sea Cucumbers { form tentacles | { with aquatic feet { 18. Eupodia with | 18. Dendrochirota IV. { _Eupodia_ { branching tentacles | =Sea Cucumbers= { { | { IX. { | +Holothuriæ+ { Sea Cucumbers { 19. Apodia with water- | 19. Liodermatida { without aquatic { lungs | { feet { 20. Apodia without | 20. Synaptida { _Apodia_ { water-lungs | ---------------------------------------------------------------- Clypeastridæ | Spatangidæ | | | Dysasteridæ | | | | | Aspidochirota | | | | | \------v------/ Synaptida | | | | | | Cassidulidæ | | | +Petalosticha+ | | | | | | | | Liodermatida | | | +Apodia+ | \------v-------/ Echinonidæ | | | | | | Galeritidæ | | | | Echinometridæ | \---------v-----------/ | | | | \------v---------/ Dendrochirota | +Eupodia+ Latistellæ +Holothuriæ+ Salenidæ |