Published online by Cambridge University Press: 20 May 2016
Systematic restudy of Lower Mississippian disparid crinoids from the midcontinental United States results in the recognition of nine valid species and one left in open nomenclature. Although disparid crinoids are not diverse, they may be locally abundant and be the dominant crinoids in certain settings. The following species are considered valid: Catillocrinus tennesseeae Shumard, Catillocrinus wachsmuthi (Meek and Worthen), Eucatillocrinus bradleyi (Meek and Worthen), Halysiocrinus bradleyi (Meek and Worthen), Halysiocrinus cumberlandensis new species, Halysiocrinus springeri Brower, Halysiocrinus tunicatus (Hall), Synbathocrinus blairi Miller, and Synbathocrinus swallovi Hall. Several species are placed into synonymy. Catillocrinus shumardi Springer and C. turbinatus are considered junior synonyms of C. tennesseeae. Halysiocrinus granuliferus and H. perplexus are regarded as junior synonyms of H. tunicatus. Synbathocrinus angularis Miller and Gurley, S. granulatus (Wood), S. granuliferus Wetherby, S. robustus Shumard, and S. troosti (Wood) are deemed junior synonyms of S. swallovi. The youngest (Meramecian) North American calceocrinids, Halysiocrinus sp., are reported, herein, from the Harrodsburg and Salem Limestones of Indiana.