568 



NORTH AMERICAN INDEX FOSSILS. 



Fig. 1907. Uintacrinus socialis. a, small individual with arms partly preserved, 

 \ % ; i>, lateral view of a larger calyx, X H » ^> analysis of calyx ; C, centrodorsal 

 plate; ^, basals ; j^, radials ; (7^ Cj, costals ; Z?jZ>2, distich als ; P^F^, pB.\ma.YS ; PPxy 

 post palmar. (After Clark. ) 



Stages. Stem more or less 5-angled; the angle of the axial canal 

 corresponding with the outer angles of the stem. Cirri very 

 numerous. Triassic-Recent. 



202. P. asteriscus Meek and Hayden. Jurassic. 



Readily identified from the joints of the column, which are thin, 

 very symmetrically pentagonal, star-shaped bodies, with rays 

 usually a little longer than wide and acutely angular at the ex- 

 tremities; the center of each joint is minutely perforated and from 

 it radiate five petaloid areas to the angles of the joint. 



