NOMEN: Chelicerata Heymons 1901 [R. Heymons. Die Entwicklungsgeschichte der Scolopender. – Zoologia, 1901, Heft 33: 1-244, Taf.I-VIII]
ORIGINAL LISTED
MEMBERSHIP (Heymons 1901):
Xiphosura + Arachnoidea 
JUNIOR CIRCUMSCRIPTIONAL SYNONYMS:
= Euarachnida Lankester
1904
= Panarachnida Lameere 1933
NON-MONOSEMANTIC CIRCUMSCRIPTIONAL SYNONYM (distinctly without †Aglaspis/fg):
= Euchelicerata Weygoldt & Paulus 1979
NON-MONOSEMANTIC CIRCUMSCRIPTIONAL SYNONYM (with uncertain position of Pantopoda):
= Cephalogradi Crampton 1928 s.str.
TYPIFIED NAME IN BASIC FORMAT: Araneus/fg (sine Pycnogonum; incl. Limulus)
TYPIFIED NAMES IN USE: -
MODERN
STATUS: 
the valid, the oldest, generally accepted name of a holophyletic taxon.
Systematic position of Chelicerata:
| Euarthropoda Trilobitomorpha Mandibulata Eucrustacea Myriapoda Hexapoda Chelicerophora Pantopoda Chelicerata |
COMMENT. In modern literature the name Chelicerata is used either in a narrow sense, for a taxon uniting Xiphosura with Arachnida only, or in a wide sense – for Chelicerophora, i.e. for a taxon which includs, besides others, Pantopoda. Initially (Heymons 1901) the name Chelicerata was published in the paper which subject was not arthropod classification, but ontogenesis and anatomy of scolopender. In this paper classification of arthropods is given very briefly; as belonging to Chelicerata there are named only Xiphosura (with a representative Limulus) and Arachnoidea (with a representative Scorpio). At that time sea spiders (Pantopoda) were sometimes placed to the class Arachnoidea (or Arachnida), sometimes separately from it. So in this case the account of subordinate taxa does not allow to understand which of the two subsequent interpretations of the name Chelicerata corresponds to the original one. However, the diagnosis of Chelicerata from the same paper gives a distinct answer to this question. According to this diagnosis, "cephalon" of Chelicerata includes 7 "Metameren", where limbs of the "Metamer 1" are lost, limbs of the "Metamer 2" are transformed to chelicerae, and limbs of the next 5 metamers are partly gnathopods, partly normal legs. As structure of Pantopoda was well-known and evidently contradicts to this diagnosis, we have to regard that originally Pantopoda were not included in Chelicerata.