144 PALEONTOLOGY OF NEW- YORK. 



Pboboscis and gummit unknown. 



Column none : afl5xed to foreign bodies by the solid base. 



This remarkable criuoid is extremely variable in the form of the basal portion, 

 which is the part usually preserved. It may be indeed that more than one species 

 are included among the forms illustrated, but I have not at this time the means of 

 satisfactory discrimination. 



In its earlier stages of growth, the base of this crinoid appears as a short pedicle 

 attached to shells and other foreign bodies, the radial plates proceeding from it as 

 from the summit of a column. It occurs singly or in groups of two or three, as 

 shown in figures 1, 2 and 3. In its successive stages, it appears with a truncated 

 base more or less rounded, but still preserving the marks of its former adhesion as 

 in figures 4, 5, 6, 7 and 8 : fig. 8 shows the radial plates and the first plates of the 

 arms, with a portion of one arm. The basal portion presents forms varying from 

 elongate turbinate to hemispheric, exhibiting a great variety of modifications and 

 distortions. 



This species differs from the one in the Lower Helderberg group mainly in its 

 larger size; the summit of the base having a diameter of an inch or more, with a 

 length of from one to two inches. 



Fig. 1, 2, 3. Tlie young growing singly and in groups of two and three, preserving the 

 radial plates above the base, which is still expanded below at its point of ad- 

 hesion. 



Fig. 4, 5, 6, 7. The bases of several individuals, showing the marks of adhesion below, and 

 having forms more or less elongated and slightly distorted. 



Fig. 8. The base, still showing the mark of adhesion at the base, and preserving the radial 

 plates with portions of the arms. 



Fig. 9. The base entirely rounded, and with the radials and first arm-plates attached. 



Fig. 10. An individual nearly entire, having a part of the base broken off, but preserving 

 the radial plates with the arms more or less entire. 



Fig. 11. Diagram of the structure, showing the base, radial and anal plates, and first plates 

 of the arms. 



Fig. 12, 13, 14 & 15. Lateral and interior views of two very symmetrical bases of this 

 species. 



Fig. 16, 17 & 18. A specimen much elongated below, and one of nearly hemispheric form. 



Fig. 19 & 20. Lateral and interior views of a remarkably elongated specimen, which may 

 perhaps prove a distinct species. 



Fig. 21 & 22. Lateral and basal view of a specimen presenting an appearance as if the 

 the upper one had grown from the interior of the base of a preceding individual. 



Geological position and locality. In the Oriskany sandstone : Cumberland, Md. 



