Cheliceramorpha

Arachnida (Arachnids)
Acarii (Mites and ticks)
Amblypygi
Araneae (Spiders)
Opiliones (Harvestmen)
Palpigradi
Pseudoscorpiones
Ricinuclei
Schizomida
Scorpiones (Scorpions)
Solifugae
Thelyphonida
Trigonotarbida

Eurypterida (Sea scorpions)

Xiphosura (Horseshoe crabs)