oaiNOiDS. 2J5 



Hydreionocrinus acanthophorus (Mekk & Worthen). 



Plate xxvi, Dg. 6. 



Zeacrinus {Hydreio>iocrinus '.^) acanthophorus Meek & Worthen, 1870: Proc. 



Acad. Nat. Sci., Phila., p. "28. 

 Zeacrinus {Hydreionocrinus ?) acanthophorus Meek & Worthen, 1875: Geol. 



Sur. Illinois, vol. V, p. 563, pi, xxiv, tigs, lla-h. 

 Hyd?-eionocrinus acanthophorus Wachstnuth & Springer, 1879: Proc. Acad.. 



Nat. Sci., Phila. (Revision, p. 131). 



Crown sabcylindrical. Dorsal cup very short, basiu- 

 shaped, concave below ; infrabasal disk small, hidden by the 

 column ; basals five, rather small, four of them of equal size, 

 the fifth somewhat smaller than the others, longer, and slightly 

 curved at the end, which is truncated for the support of one 

 of the anal pieces ; radials rather large, much wider above than 

 below, strongly curved, straight along the upper edge. First 

 brachials somewhat smaller than the radials, pentagonal. Arms 

 rather slender, bifurcating on the second plate. Plates of the 

 anal side arranged as in Woodocrinus. ' Ventral sac about 

 equaling the length of the arms, relatively narrow, but gradu- 

 ally widening upward, until near the top it abruptly spreads 

 out horizontally to about the greatest width of the calyx ; the 

 upper surface is flat, composed of numerous small polygonal 

 pieces, and bordered by a dozen or more large, flattened ossi- 

 cles, which bear long, heavy spines directed outward all around. 

 Surface of calyx smooth. Stem small. 



Horizon and localities — Upper Carboniferous, Upper 

 Coal Measures : Kansas City. 



Hydreionocrinus pentagonus Miller & Gubley. 



Hydreionocrinus pentago7ius Miller & Gurley, 1890 : Jour. Cincinnati Soc. 

 Nat. Hist., vol. Xlll, p. 17, pi. ii, figs. 6 7. 



Dorsal cup similar to H acanthophorus^ but basal concav- 

 ity rather deeper and pentagonal in shape. 



Horizon and locality. — Upper Carboniferous, Upper Coal 

 measures : Kansas City. 



