Assertion: eurypterid | /r/HasProperty | unique
Facets:
Source sentences:
text: In the sediments which it has been demonstrated (by myself or others), were with more or less certainty derived from Appalachia, the eurypterids are either unique, showing no relation to known species in North America or other continents, or else they show phyletic relationship inter se, the species of later faunas having certain characteristics in common with those of (generally the mature forms of) earlier faunas.