Taxonomic names from W. B. Clark and M. W. Twitchell 1915

  • Amblypygus merrilli, W. B. Clark and M. W. Twitchell 1915 [Echinoneidae]
  • Aspidura idahoensis, W. B. Clark and M. W. Twitchell 1915 [Ophiuridae]
  • Asterias dubium, Whitfield 1877 [Asteriidae]
  • Asterias lincki, Sears 1905 [Asteriidae]
  • Asterias remondii, Gabb 1869 [Asteriidae]
  • Asterias stellionura, Sears 1905 [Asteriidae]
  • Asternata, suborder [Echinoidea]
  • Astrodapsis arnoldi, W. B. Clark and M. W. Twitchell 1915 [Echinarachniidae]
  • Astrodapsis jacalitosensis, Arnold 1909 [Echinarachniidae]
  • Atheneidae, family [Atheneidae]
  • Botriopygus alabamensis, Clark 1891 [Nucleolitidae]
  • Bourgueticrinus alabamensis, De Loriol 1882 [Bourgueticrinidae]
  • Breynella, Gregory [Cassidulidae]
  • Breynella gregoryi, W. B. Clark and M. W. Twitchell 1915 [Pliolampadidae]
  • Brissopsis poriferus, Ravenel 1848 [Schizasteridae]
  • Brissopsis rimulatus, Ravenel 1848 [Schizasteridae]
  • Calycina, suborder (Gregory 1900) [Echinoidea]
  • Cardiaster curtus, W. B. Clark and M. W. Twitchell 1915 [Holasteridae]
  • Cassidulus (Pygorhynchus) () [Nucleolitidae]
  • Cassidulus (Pygorhynchus) alabamensis, W. B. Clark and M. W. Twitchell 1915 [Cassidulidae]
  • Cassidulus (Pygorhynchus) carolinensis, W. B. Clark and M. W. Twitchell 1915 [Cassidulidae]
  • Cassidulus (Pygorhynchus) georgiensis, W. B. Clark and M. W. Twitchell 1915 [Faujasiidae]
  • Cassidulus (Pygorhynchus) gouldii (Bouve 1846) [Cassidulidae]
  • Cassidulus (Rhynchopygus) (d'Orbigny 1856) [Faujasiidae]
  • Cassidulus (Rhynchopygus) conradi, Couper 1850 [unclassified species]
  • Cassidulus (Rhynchopygus) depressus, W. B. Clark and M. W. Twitchell 1915 [Faujasiidae]
  • Cassidulus (Rhynchopygus) holmsei, W. B. Clark and M. W. Twitchell 1915 [Pliolampadidae]
  • Cassidulus (Rhynchopygus) ravenli, W. B. Clark and M. W. Twitchell 1915 [Pliolampadidae]
  • Cassidulus abruptus, Conrad 1860 [Cassidulidae]
  • Cassidulus amygdala, Desor 1858 [Cassidulidae]
  • Cassidulus bassleri, W. B. Clark and M. W. Twitchell 1915 [Cassiduloida]
  • Cassidulus berryi, W. B. Clark and M. W. Twitchell 1915 [Cassiduloida]
  • Cassidulus conoideus, W. B. Clark and M. W. Twitchell 1915 [Cassiduloida]
  • Cassidulus florealis (Morton 1833) [Cassiduloida]
  • Catopygus conradi, Couper 1850 [Faujasiidae]
  • Catopygus oviformis, W. B. Clark and M. W. Twitchell 1915 [Pliolampadidae]
  • Catopygus patelliformis, Bouvé 1851 [Pliolampadidae]
  • Cidaris alabamensis, Morton 1846 [Cidaridae]
  • Cidaris blandis, De Gregorio 1890 [Cidaridae]
  • Cidaris dilleri, W. B. Clark and M. W. Twitchell 1915 [Cidaridae]
  • Cidaris dixiensis, Cragin 1893 [Cidaridae]
  • Cidaris georgiana, W. B. Clark and M. W. Twitchell 1915 [Cidaridae]
  • Cidaris hemigranosus, Shumard 1860 [Cidaridae]
  • Cidaris mortoni (Conrad 1850) [Cidaridae]
  • Cidaris plumasensis, W. B. Clark and M. W. Twitchell 1915 [Cidaridae]
  • Cidaris pratti, W. B. Clark and M. W. Twitchell 1915 [Cidaridae]
  • Cidaris shastensis, W. B. Clark and M. W. Twitchell 1915 [Cidaridae]
  • Cidaris smithi, W. B. Clark and M. W. Twitchell 1915 [Cidaridae]
  • Cidaris tehamensis, W. B. Clark and M. W. Twitchell 1915 [Cidaridae]
  • Cidaris thouarsii, Valencienncs 1846 [Cidaridae]
  • Clypeaster gabbi, Rémond 1863 [Scutellidae]
  • Clypeastrina, suborder [Exocycloida]
  • Coelopleurus aldrichi, W. B. Clark and M. W. Twitchell 1915 [Arbaciidae]
  • Coelopleurus sloani, W. B. Clark and M. W. Twitchell 1915 [Arbaciidae]
  • Coptosoma mortoni (de Loriol 1887) [Phymosomatidae]
  • Cottaldia rotula, W. B. Clark and M. W. Twitchell 1915 [Echinoidea]
  • Cyphosoma hilli (Clark 1891) [Phymosomatidae]
  • Cyphosoma volanum, Cragin 1893 [Phymosomatidae]
  • Cyphosomatidae, family [Cyphosomatidae]
  • Dendraster arnoldi, W. B. Clark and M. W. Twitchell 1915 [Dendrasteridae]
  • Dendraster coalingaensis, W. B. Clark and M. W. Twitchell 1915 [Dendrasteridae]
  • Dendraster excentricus (Eschscholz 1826) [Dendrasteridae]
  • Dendraster gibbsii (Rémond 1863) [Dendrasteridae]
  • Dendraster interlineatus (Stimpson 1856) [Scutellidae]
  • Diadema texanum, Roemer 1852 [Pseudodiadematidae]
  • Diademoidea, order [Diademoidea]
  • Dicyclica, subclass [Crinoidea]
  • Diplopodia streeruvitzi, Cragin 1893 [Pseudodiadematidae]
  • Diplopodia taffi, Gragin 1893 [Pseudodiadematidae]
  • Diplothecanthus, Duncan [Clypeasteridae]
  • Diplothecanthus dalli, W. B. Clark and M. W. Twitchell 1915 [Clypeasteridae]
  • Diplothecanthus rosaceus (Linnaeus 1758) [Clypeasteridae]
  • Dumblea symmetrica, Craigin 1893 [Pseudodiadematidae]
  • Echinanthus georgiensis, W. B. Clark and M. W. Twitchell 1915 [Cassidulidae]
  • Echinanthus mortonis (Michelin 1850) [Cassiduloida]
  • Echinina, suborder () [Camarodonta]
  • Echinobrissus angustatus, W. B. Clark and M. W. Twitchell 1915 [Nucleolitidae]
  • Echinobrissus expansus, Clark 1891 [Nucleolitidae]
  • Echinocardium deperessum, W. B. Clark and M. W. Twitchell 1915 [Loveniidae]
  • Echinocardium gothicus (Ravenel 1848) [Loveniidae]
  • Echinocidaris, Duncan [Arbaciidae]
  • Echinocyamus huxleyanus, Meyer 1886 [Fibulariidae]
  • Echinocyamus meridionalis, W. B. Clark and M. W. Twitchell 1915 [Fibulariidae]
  • Echinocyamus parvus, Emmonds 1858 [Fibulariidae]
  • Echinocyamus texanus, W. B. Clark and M. W. Twitchell 1915 [Fibulariidae]
  • Echinocyamus vaughani, W. B. Clark and M. W. Twitchell 1915 [Fibulariidae]
  • Echinolampas aldrichi, W. B. Clark and M. W. Twitchell 1915 [Echinolampadidae]
  • Echinolampas appendiculatus, Emmons 1858 [Echinolampadidae]
  • Echinus infulatus, Morton 1833 [Arbaciidae]
  • Echinus pentaporus, Gmelin 1788 [Mellitidae]
  • Enallaster obliquatus, Clark 1893 [Toxasteridae]
  • Encrinus hyatti, W. B. Clark and M. W. Twitchell 1915 [Encrinidae]
  • Epiaster whitei, Clark 1891 [Paleopneustidae]
  • Eupatagus carolinensis, W. B. Clark and M. W. Twitchell 1915 [Brissidae]
  • Eupatagus floridanus, W. B. Clark and M. W. Twitchell 1915 [Brissidae]
  • Flexibilia, order (K. A. Zittel 1895) [Crinoidea]
  • Gagaria americana, W. B. Clark and M. W. Twitchell 1915 [Temnopleuroida]
  • Galerites oregonensis, Dana 1849 [Galeritidae]
  • Goniopygus zitteli, Clark 1891 [Arbaciidae]
  • Hemiaster beecheri, W. B. Clark and M. W. Twitchell 1915 [Hemiasteridae]
  • Hemiaster bexari, W. B. Clark and M. W. Twitchell 1915 [Hemiasteridae]
  • Hemiaster calvini, Clark 1893 [Hemiasteridae]
  • Hemiaster comanchei, W. B. Clark and M. W. Twitchell 1915 [Hemiasteridae]
  • Hemiaster conradi, Bouvé 1851 [Schizasteridae]
  • Hemiaster elegans, Shumard 1853 [Hemiasteridae]
  • Hemicidaris intumescens, Clark 1893 [Hemicidaridae]
  • Hemipatagus argutus, W. B. Clark and M. W. Twitchell 1915 [Loveniidae]
  • Hemipatagus subrostratus, W. B. Clark and M. W. Twitchell 1915 [Loveniidae]
  • Heterodiadema ornatum, W. B. Clark and M. W. Twitchell 1915 [Pseudodiadematidae]
  • Holaster mortoni, Conrad 1850 [Brissidae]
  • Holaster simplex, Shumard 1853 [Holasteridae]
  • Holectypus cragini, W. B. Clark and M. W. Twitchell 1915 [Holectypidae]
  • Holectypus pealei, W. B. Clark and M. W. Twitchell 1915 [Holectypidae]
  • Hypodiadema elegans, W. B. Clark and M. W. Twitchell 1915 [Pseudodiadematidae]
  • Isocrinus californicus, W. B. Clark and M. W. Twitchell 1915 [Isocrinidae]
  • Isocrinus smithi, W. B. Clark and M. W. Twitchell 1915 [Holocrinida]
  • Laganum archerensis, W. B. Clark and M. W. Twitchell 1915 [Laganidae]
  • Laganum dalli, W. B. Clark and M. W. Twitchell 1915 [Laganidae]
  • Laganum eldridgei, W. B. Clark and M. W. Twitchell 1915 [Laganidae]
  • Laganum floridanum, W. B. Clark and M. W. Twitchell 1915 [Neolaganidae]
  • Laganum johnsoni, W. B. Clark and M. W. Twitchell 1915 [Laganidae]
  • Leptarbacia, W. B. Clark and M. W. Twitchell 1915 [Hemicidaridae]
  • Leptarbacia argutus, W. B. Clark and M. W. Twitchell 1915 [Hemicidaridae]
  • Linthia alabamensis, W. B. Clark and M. W. Twitchell 1915 [Schizasteridae]
  • Linthia wilmingtonensis, W. B. Clark and M. W. Twitchell 1915 [Schizasteridae]
  • Macropneustes carolinensis, W. B. Clark and M. W. Twitchell 1915 [Unifasciidae]
  • Marsupites americanus, Springer 1911 [Marsupitidae]
  • Marsupitidae, family [Marsupitidae]
  • Micropsis lineatus, W. B. Clark and M. W. Twitchell 1915 [Phymosomatidae]
  • Nucleolites lyelli, Conrad 1850 [Faujasiidae]
  • Oligopygus floridanus, W. B. Clark and M. W. Twitchell 1915 [Oligopygidae]
  • Ophioglypha utahensis, W. B. Clark and M. W. Twitchell 1915 [Ophiuridae]
  • Orthechinus, Gauthier [Cyphosomatidae]
  • Orthechinus pretiosus, W. B. Clark and M. W. Twitchell 1915 [Glyphocyphidae]
  • Orthopsis occidentalis, Cragin 1893 [Orthopsidae]
  • Orthopsis planulata, W. B. Clark and M. W. Twitchell 1915 [Orthopsidae]
  • Paractinopoda, order [Paractinopoda]
  • Paraster armiger (W. B. Clark and M. W. Twitchell 1915) [Schizasteridae]
  • Pentacerotidae, family [Pentacerotidae]
  • Pentacrinus asteriscus, Meek and Hayden 1858 [Crinoidea]
  • Pentacrinus bryani, Gabb 1876 [Crinoidea]
  • Pentacrinus shastensis, W. B. Clark and M. W. Twitchell 1915 [Crinoidea]
  • Pentacrinus tehamaensis, W. B. Clark and M. W. Twitchell 1915 [Crinoidea]
  • Pentacrinus whitei, Clark 1893 [Crinoidea]
  • Pentagonasteridae, family [Pentagonasteridae]
  • Periarchus protuberans, W. B. Clark and M. W. Twitchell 1915 [Protoscutellidae]
  • Pericosmus spatiosus, Ravenel 1848 [Brissidae]
  • Phanerozoma, order [Phanerozoma]
  • Phyllacanthus mortoni (Conrad 1850) [Cidaridae]
  • Pinnata, suborder [Crinoidea]
  • Plagionotus, Agassiz 1847 [unclassified genus]
  • Plagionotus holmesii, McCrady 1855 [Brissidae]
  • Plagionotus ravenelianus, McCrady 1855 [Brissidae]
  • Psammechinus cingulatus, Clark 1891 [Echinidae]
  • Psammechinus exoletus, McCrady 1857 [Echinidae]
  • Pseudodiadema emersoni, Clark 1893 [Pseudodiadematidae]
  • Pygorhynchus rugosus, Ravenel 1848 [Pliolampadidae]
  • Pygurus geometricus (Morton 1833) [Cassiduloida]
  • Pyrina parryi, Hall 1857 [Echinoneidae]
  • Rhizocrinus, Sars [Bourgueticrinidae]
  • Rhizocrinus cylindricus, Weller 1907 [Bourgueticrinidae]
  • Salenia texana, Credner 1891 [Saleniidae]
  • Santeelampas carolinensis, W. B. Clark and M. W. Twitchell 1915 [unclassified species]
  • Sarsella, Pomel [Spatangidae]
  • Sarsella gregoryi, W. B. Clark and M. W. Twitchell 1915 [Spatangidae]
  • Schizaster americana, W. B. Clark and M. W. Twitchell 1915 [Schizasteridae]
  • Schizaster atropos (Lamarck 1816) [Schizasteridae]
  • Schizaster floridanus, W. B. Clark and M. W. Twitchell 1915 [Schizasteridae]
  • Scutella alberti (Conrad 1842) [Scutellidae]
  • Scutella andersoni, W. B. Clark and M. W. Twitchell 1915 [Scutellidae]
  • Scutella caroliniana, Ravenel 1841 [Mellitidae]
  • Scutella crustuloides, Morton 1833 [Laganidae]
  • Scutella lyelli, Conrad 1834 [Protoscutellidae]
  • Scutella macrophora, Ravenel 1842 [Mellitidae]
  • Scutella mississippiensis, W. B. Clark and M. W. Twitchell 1915 [Protoscutellidae]
  • Scutella pileussinensis, Ravenel 1844 [Protoscutellidae]
  • Scutella quinquefaria, Say 1825 [Protoscutellidae]
  • Scutella tuomeyi, W. B. Clark and M. W. Twitchell 1915 [Scutellidae]
  • Scutellaster cretaceus, Cragin 1895 [Echinarachniidae]
  • Sismondia alta, Conrad 1865 [Protoscutellidae]
  • Sismondia arnoldi, W. B. Clark and M. W. Twitchell 1915 [Fibulariidae]
  • Sismondia coalingaensis, W. B. Clark and M. W. Twitchell 1915 [Fibulariidae]
  • Sismondia conradi, Cotteau 1891 [Protoscutellidae]
  • Sismondia plana, Conrad 1865 [Protoscutellidae]
  • Sternata, suborder [Echinoidea]
  • Stomechinus hyatti, Clark 1893 [Stomechinidae]
  • Strongylocentrotus purpuratus, Arnold 1903 [Strongylocentrotidae]
  • Toxaster texanus, Roemer 1849 [Toxasteridae]
  • Toxopneustes variegatus (Lamarck 1816) [Toxopneustidae]
  • Triplechinidae, family [Triplechinidae]
  • Uintacrinidae, family [Uintacrinidae]
  • Uintacrinus socialis, Grinnell 1876 [Uintacrinidae]
  • Zygophiurae, order [Zygophiurae]