Dodatak:Popis prakliještara, X
Xa
uredi†Xaniopyramis Siveter & Selden, 1987
uredi- Xaniopyramis linseyi Siveter and Selden, 1987[1]
Animalia → Arthropoda → Merostomata → Xiphosurida → Moravuridae
Xi
urediRod Xiphosura Gronovius, 1764
uredi- Sinonim = Limulus O.F. Müller, 1785
Razred Xiphosura Latreille, 1802
uredi- sinonim = Merostomata Woodward, 1866
Red Xiphosurida R. & E. Richter, 1924
uredi- Limulidae Leach, 1819