LOWER HELDERBEKG ROCKS. 123 



Fig. 15. The exterior of the base of an individual of this species. 



Fig. 16. The interior of the same. 



Fig. 17. Profile or lateral view of the same. 



Fig. 18. The interior of a large specimen. 



Geological position and locality. In the upper part of the shaly limestone of the 

 Lower Helderberg group, and in the " Scutella limestone" : Helderberg mountains, 

 and Schoharie. 



Aspidocrinns callosns ( n. s.). 



Plate V. Fio. 13 & 14. 



Base small, rounded below, somewhat quadrangular and much thickened 



above ; having prominent rounded points or nodes, with narrow spaces 



between. 



This form bears as much analogy to the root as to the calyx of a crinoid, and may 

 perhaps be only this part of the individual. Other similar forms exhibit a variable 

 number of thickened marginal nodes; although there is no appearance of small 

 rootlets, as is usual, and the point of attachment for the column is quite anall. 



Fig. 13 & 18. Interior and exterior views of the specimen described. 



Geological position and locality. In the shaly limestone of the Lower Helderberg 

 group : Helderberg mountains, and Schoharie. 



Aispidocrinns di^tatns ( n. s.). 



Plate V. Fio. 19 & 20. 



The specimen figured has, in some respects, so much the character of a root, that 

 it is not easy to suppose it to have been anything else; but the mode of attachment 

 of the column is precisely as in the calyx of a crinoid, and entirely unlike ordinary 

 roots of these fossils. The divisions terminate abruptly, without any evidence of 

 prolonged rootlets, or of any mode of attachment whatever upon the lower side. 



Fig. 19 & 20. Upper side and profile view of the specimen. 



Geological position and locality. In the shaly limestone of the Lower Helderberg 

 group, Schoharie. 



