Revised systematics of Palaeozoic ‘ horseshoe crabs’ and the myth of monophyletic Xiphosura Author Lamsdell, James C. text Zoological Journal of the Linnean Society 2013 2012-12-18 167 1 1 27 http://dx.doi.org/10.1111/j.1096-3642.2012.00874.x journal article 10.1111/j.1096-3642.2012.00874.x 0024-4082 5292231 PYCNOGONIDA LATREILLE, 1810 [= ARACHNOPODA DANA, 1853 ] Diagnosis: Chelicerata with all body segments retaining dorsal differentiation; external proboboscis developed around mouth; appendage III modified into ovigers; abdomen generally reduced.