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PRELIMINARY NOTICE 



OF SOME OF THE SPECIES OF CRINOIDEA KNOWN IN THE 

 UPPER HELDERBERG AND Hi^ MILTON GROUPS OF NEW-YORK. 



CRINOIDEA. 



GENUS EDRIOCRINUS (Hall). 



In the third volume of the Palaeontology of New- York*, I have 

 proposed the name Edriocrinus for some species of Crinoidea which 

 are apparently destitute of a column, but which in their young state 

 are affixed by their basal plates, and afterwards become free. One 

 of the described species^ inits earlier stages of growth, often occurs 

 in groups of two or three individuals, firmly adhering to some foreign 

 body by a broad base of attachment. 



The species described are from the Lower Helderberg limestones 

 and from the Oriskany sandstone. 



In the limestone of the Upper Helderberg group there is a similar 

 form, with more elongated base, which is sometimes rounded, and 

 resembles a short column; but so far as I am able to determine from 

 the specimens examined, the species is sessile, having the structure 

 of those already described, without a jointed column. 



1. Figure of a specimen, natural size, showing base and first radial plates. 



2. View of the summit of the specimen. 



• Palaeontology, Vol. iii, p. 119. 



