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ART. XI. — Descriptions of seven new species of CRmowEA. from the suh-carhoniferous 

 limestone of Iowa and Illinois. By David D. Owen, M. D., and Benjamin F. 

 Shumard, M. D. 



Genus PLATYCRINUS, {Miller.) 



Platycrinus Americanus. (New sp.) 



PI. XL fig. 1, a, &. 



Calyx. — Sub-globose, surface ornamented with numerous prominent granulse. 

 Basal plate pentagonal, flattened ; surface for the attachment of the column small, 

 round, finely striated in radii, with a minute central perforation. From the edge of 

 this surface five principal rows of granulse radiate to each angle of the plate, the 

 intervening spaces being likewise granulated. Superior plates five, rather broad, 

 increasing slightly in width from below upwards ; articular facet for the arms small 

 and shallow. The granulse are usually disposed over the surface of these plates, as 

 follows : a row commences at each of the inferior angles, and terminates at the base 

 of the arms, marking out three triangular spaces on each piece, which are a]so 

 studded with granulse. 



This encrinite is nearly allied to Platycrinus granulatus, (Miller,) but it can be 

 readily distinguished from that species, by its more depressed form, smaller size and 

 flattened basal plate. 



Formation and Locality. — It occurs in the quarries near Burlington, Iowa, in the 

 encrinital beds of the carboniferous limestone, just above the oolitic members of this 

 formation. It is associated with Spirifer striatus, Orthis Miclielini, Productus 

 punctatus and other carboniferous forms. 



EXPLANATION OF FIGURES. 

 Fig. 1. a. View of the base of the calyx. 

 " h. Side view. 



Genus POTERIOCRINUS, {MUler.) 



POTERIOCRINUS RHOMBIFERUS. (New sp.) 



PL XL fig. 2, a, h, c. 



Calyx. — Conical, plates massive, surface garnished with heavy ridges. Basal 

 plate pentagonal, small, scarcely a line in diameter, entirely concealed from view 

 when the supra columnar joint remains attached. 



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