CLASS III CRINOIDEA 213 



Family 3. Anomalocrinidae Wachsmuth and Springer. 

 Monocyclic ; basalsfive. Calyx hroadly rotund in form. Tegmen strong, composed 

 chieflg of large modified amhulacrals and interamMacrals, extending posteriorly into 

 a large expanding anal tube or sac. Radiais very large, two of them—the right 

 posterior and left antero-lateral— Compound, all of them laterally in contad ; inf erradial 

 rarely larger tlian the superradial; the lower tuhe-plate, or anal x, resting in the 

 angle formed hy the superradial to the right, and the upper end of the simple radial 

 to the left, hut not entering the cup. Radial facets circular and very small. Arms 

 relatively slender, uniserial, and bifurcating several times at somewhat irregulär 

 intervals. Small armlets given off from each arm-joint on one side only, alter nately 

 in the successive dichotoms. Column strong, round, attached by an encrusting root. 

 Ordovician. 



Anomalocrinus M. and W. (Ataxocrinus Lyon). The only genus of the 

 family. The Statements heretofore current that one radial is often longi- 

 tudinally bisected, and that the.re is a small supplementary piece within 

 the basal ring, are based on abnormal specimens only. Ordovician ; North 

 America. 



Family 4. Cremacrinidae Ulrich (Galceocrinidae M. and W.). 



Monocyclic Inadunata, in which a bilateral symmetry along the left anterior 

 radius and right posterior interradius has been superinduced in conjunction with 

 bending of the crown on the stem in such a way that the right posterior interray lies 

 along the stem ; with the left anterior, right posterior and right anterior radials Com- 

 pound ; with anal x (IRA) shifted over the right posterior radius, usually into the 

 right posterior interradius, and supporting a massive tube ; with three, rarely four, 

 arms, of which two are as a rule peculiarly modified and bear armlets or pinnules. 

 (From Bather, " The Crinoidea of Gotland.") Ordovician to Lower Carbon- 

 iferous. 



Cremacrinus Ulr. (Castocrinus Ringueb.). B distinct, all entering into the 

 articular surface of the stem. The right posterior, and right anterior super- 

 radials joined by ill-defined close suture, each abutting with one side on the 

 adjacent large simple R. The lower plate of the tube supported by the 

 right posterior superradial only, while the right anterior superradial supports 

 the first brachial of the right anterior arm. The right posterior and right 

 anterior superradials separated from one another, and also from the ventral 

 tube, by the right posterior and right anterior R. Arms four. Ordovician ; 

 North America. Type, C. punctatus Ulr. 



Euchirocrinus Meek and Worthen (Cheirocrinus Hall, wow Eichwald ; Pro- 

 clivocrinus Ringueb.). B unfused, or perhaps sometimes the left posterior fused 

 with the left anterior one. The right posterior and right anterior super- 

 radials fused in a T-shaped piece, which abuts with either wing on the 

 Corners of the large simple R. The right posterior and right anterior 

 inferradials separated from one another and from the tube by the T-piece ; 

 tube supported by the whole Upper margin of the latter. Arms three. 

 Silurian ; North America. Type, E. chrysalis (Hall). 



Deltacrinus Ulrich {Cheirocrinus Salter, nom. nudum ; Calceocrinus Hall em. 

 Ringueberg). Left posterior basal fused with the left anterior one ; the 



