282 paljEONtologt of new-yokk. 



There is some difficulty in making out the entire structure, since the plates usually adhere 

 very closely, and some of the pectoral and intcrbrachial plates are very small. The 

 important parts, however, and the plates proceeding to the arms, are readily and clearly 

 determined. 



This fossil is usually found destitute of the column ; and I have not been able to decide 

 satisfactorily whether all the fragments found with it are parts of the same, or belong to 

 two species. The first, which evidently belong to this species, and form the upper part 

 of the column, consist of joints, having a small base resting upon the broader disc of 

 the next one below, giving more freedom of motion. Other portions have the upper sur- 

 face of the disc excavated, and the column appears to be composed of a series of cups, 

 alternating in size and placed one within the other, having the upper edges either smooth 

 or fimbriated (figs. 1 a and 1 6, pi. 78). These columns have usually a distinct round 

 alimentary canal, with the upper and lower siuface marked by fine rays, more deeply 

 impressed near the edge. In other parts of the column, where the plates are more nearly 

 equal in size, the upper and lower surfaces have a pentapetalous impression or elevation 

 radiating from the alimentary canal. This character, in fine, becomes the prominent and 

 characteristic one of the greater proportion of the fragments of columns which we find ; 

 and they present all the variety of broad equal smooth joints with even surfaces, or of 

 similar joints with a thin plate interposed, and of columns composed of moniliform joints 

 with smaller ones between ; or of distant rounded joints, sometimes deviating slightly from 

 a cylindrical form. All the important varieties are illustrated by figures. 



Plate LXXVII. 



Fig. 1 ffl. A fragment of stone with two small specimens, preserving the tentaculated fingers. 



Fig. I b. Figure of a larger specimen, showing the character of the plates and their arrangement 



more distinctly. The bases of the fingers, with about five or six joints, are preserved in this 



specimen. 

 Fig. 1 c. The upper e.xtremity or crown of the last specimen, showing the capital plates. 

 Fig. 1 d. The same enlarged. 

 Fig. 1 e. A portion of the surface enlarged, showing the form and character of the plates, and the strong 



radiating ridges. 

 Fig. 1 / An enlarged figure, showing the structure and arrangement of the plates as described. A 



small portion only of ihe plates of the fingers are represented, but there are no subdivisions 



beyond this point. 



Plate LXXVIII. 



Fig. 1 a. A figure of a specimen, preserving a small portion of the column and the entire length of 



the fingers. 

 Fig. 1 b. Fragments of columns, composed of alternating larger and smaller discs with angular edges. 



suggesting that it may be an .flpiocrinite, which proves otherwise on examination. From his account, it would 

 appear that the first specimen was found at Cincinnati, in 1837. This species is probably one of those named in Dr. 

 Owen's Catalogue ; but I have never seen a description of the same, nor received a specimen with the name attached. 



