298 Wood — Crinoid from the Hamilton of Charlestown. Ind. 



spine is a variable number of plates which bear low spines or 

 nodes. Other plates of the tegmen appear to have been 

 smooth. Anns located half way between the summit and the 

 periphery, its plates not preserved. 



Base of the calyx flat, a feature due to a thickening of the 

 basals. This thickening extends over about two-thirds of the 

 surface of each basal and is produced in a thin rim whose 

 margin is parallel with that of the plate. 



Diagram to show arrangement of calyx plates of Gennazocrinus carinatus, sp. nov. 



The lower half of each radial and the primary anal plate are 

 ornamented by a projecting crescentic ridge thickened at the 

 center and dying out or terminated by a spine at the sides. 

 From the outer curve of this ridge carinas pass to the upper 

 sides and angles of the radial, where they meet similar carinas 

 of the higher brachials. The brachials and interbrachials bear 

 strong carinas which pass from the center to each side of the 

 plate, and others, less prominent, directed toward but not 

 reaching the angles. 



Column circular, occupying one-half the area of the basals. 

 Axial canal pentalobate and having a diameter one-third that 

 of the column. 



Observations. — This species is remarkable for its elaborate 

 'and delicate surface ornamentation, the thin carinas rising at 

 right angles to the surface and sometimes a millimeter or more 

 in height. 



