FROM THE CORAL RAG. 219 



Affinities and differences. — This species most nearly resembles StomecJiinus c/yratus, but 

 is distinguished from it by the absence of the naked median depressions in the iuter- 

 ambulacral areas, which gives such a remarkable lobed character to the surface of its test ; 

 by the absence of the circles of granulations around the base of the tubercles ; and the 

 naked appearance which the surface of the plates presents, in consequence of the almost 

 total absence of this granular ornamentation, and w^hich is expressed by its specific 

 name nudus. 



LocalHy and Straiigraphical position. — This Echinite was collected in Wiltshire, but 

 I have not been able to ascertain the correct locality ; it appears to have been obtained from 

 the Coral Rag, although this is not certain. 



29 



