Consequently, we may with assurance infer a common derivation of all those orders from a common Primæval Crab, which was essentially like the Nauplius of the present day. SYSTEMATIC SURVEY _Of the 7 Legions and 20 Orders of Crabs, or Crustacea._ -------------------------+--------------------------+----------------------+-------------- _Legions of the_ | _Orders of the_ | _Systema Name_ | _Name of a_ _Crustaceæ._ | _Crustaceæ._ | _of the Orders._ | _Genus as an_ | | | _example._ -------------------------+--------------------------+----------------------+-------------- I. ENTOMOSTRACA, _Lower Crustacea_, or Segmented Crabs (not passing through the actual Zoëa form in youth). ------------------------------------------------------------------------------------------ +I. Branchiopoda+ { 1. Primæval Crabs 1. Archicarida Nauplius Gill-footed Crabs { 2. Leaf-foot Crabs 2. Phyllopoda Limnetis { 3. Trilobites 3. Trilobita Paradoxides { 4. Water Fleas 4. Cladocera Daphnia { 5. Bivalve Crabs 5. Ostracoda Cypris +II. Pectostraca+ { 6. Barnacle Crabs 6. Cirripedia Lepas Fixed Crabs { 7. Root Crabs 7. Rhizocephala Sacculina +III. Copepoda+ { 8. Boatmen Crabs 8. Eucopepoda Cyclops Oar-footed Crabs { 9. Fish Lice 9. Siphonostoma Lernæocera +IV. Pantopoda+ {10. No-body Crabs 10. Pycnogonida Nymphon No-body Crabs { +V. Pœcilopoda+ {11. Spear-tails 11. Xiphosura Limulus Shield Crabs {12. Giant Crabs 12. Gigantostraca Eurypterus ------------------------------------------------------------------------------------------ II. MALACOSTRACA, _Higher Crustacea_, or Mailed Crabs (passing through the Zoëa form in youth). ------------------------------------------------------------------------------------------ +VI. Podophthalma+ {13. Zoëa Crabs 13. Zoëpoda Zoëa Stalk-eyed Mailed {14. Split-legged Crabs 14. Schizopoda Mysis Crabs {15. Mouth-footed Crabs 15. Stomatopoda Squilla {16. Ten-footed Crabs 16. Decapoda Peneus