SYSTEMATIC REVIEW. 



CRINOIDEA. 



UINTACRINIB^.' 



Calyx unsymmetrical, without coliimu. Basis monocyclic. Basals 

 five, inclosing a centro-dorsal plate, Radials 5x3. Interradials numer- 

 ous, the lowest between the second radials. Arms 5x2, very long, 

 with pinnules. 



UINTACRINUS Grinnell. 



UiNTACRiNUS sociALis Grinnell. 



Plate I, Figs, la-c; Plate ii, Figs. la-e. 



Uintacrinus socialis Grinnell, 1876. Amer. Jour. Sci., 3d ser., vol. 12, pp. 81-83, PI. 



IV, Figs. l-2b. 

 Uintacrinus socialis Meek, 1876. U. S. Geol. and Geog. Survey of the Territories, 



Bull. vol. 2, pp. 375-378, Figs. A-B. 



Determinative characters. — Calyx subglobose, composed of numerous 

 thin, slightly convex plates, joined together by channeled sutures and 

 without distinct surface markings. Column wanting. Basis composed 

 of a small pentagonal centro-dorsal plate, surrounded by a circle of five 

 small similar basals. Encircling the pentagonal base and alternating 

 with the basals are five large radials, hexagonal in outline and wider 

 than high. Succeeding the primary radials are secondary and tertiary 

 radials, the latter axillary in form. The primary radials alone are in 

 contact, the others being separated by interradials. Succeeding the 

 radials are several distichals, which gradually change to true rounded 

 brachials, forming ten long arms. Between the distichals are two 

 large interdistichals, situated one above the other. From the second 

 distictal, which is axillary in form, a row of plates diverges interra- 

 dially, alternating with similar plates from the same distichal of the 

 adjacent area. From the fourth distichal a like row of plates diverges 

 radially, alternating with similar plates from the same distichal of the 

 other half of the same area. Iliglier up other rows diverge both radially 



' Thofamilyof tbeUintacrinidie, as characterizeil byvon Zittelinhis "HandbuchderPaleontologie," 

 iucludes only two species, Uintacrinus gocialis Grinnell, from the Cretaceoua of Utah and Kansas, 

 and U. westfalicus Schliiter from the Cretaceous of Wcstfalia. The genera Uintacrinus and War- 

 Bupites alone among Mesozoic types aflord i)oiuts for comparison with the Paleozoic crinoids. 

 Neumayr in " Die Stamme des Thierrciches '' considers the difficulty of bringing them into a consistent 

 classification with the other crinoids but suggests several points of relationship between Uiutacriuus 

 and the Ichthyocrinidie. 



21 



