ECHINODERMATA—CRINOIDEA. 



511 



zag outline. Arms 10, rarely 9 ; pinnules robust, resembling small 

 armsand widely separated. Ventral sac club-shaped. Mississippic. 



42. D. pleias (Hall). (Fig. 1824, e.) Mississippic. 

 Calyx rapidly expanding. Arms composed of a single row of 



subcuneate plates. Surface of plates smooth or finely granulose. 

 Column subpentagonal, composed of alternately thicker and thinner 

 plates. 



Waverly of Ohio. 



43. D. aegina (Hall). (Fig. 1824,/.) Mississippic. 

 Arms composed of elongate joints, which give rise to jointed 



branches from near the margin of their longer side. Surface of 

 plates granulose. 

 Waverly of Ohio. 



XIX. WooDOCRiNUS de Koninck. 



Calyx saucer-shaped. IB 5, small. B large, curving inward 

 below with the IB to form the concavity around the column. R 

 truncated above. Brachials truncated below. Arms bifurcating, 



Fig. 1826. Woodocrinus aqualis,y(^l 

 (After Meek and Worthen.) 



Fig. 1827. Woodocrinus elegans^ an- 

 terior side. (After Hall.) 



uniserial and closely in contact laterally. Anal area composed of 

 several rows of plates. Column round. Mississippic. 



44. W. troostanus (Meek and Worthen). Mississippic. 



Entire length to extremity of arms about one and one half inches. 



