POTERIOCRmrDiE.— POTERIOCKraUS. 35 



with the enormous oral tube of the P. crassus,P\. 9, fig. 1, its size will not deter the 

 Palceontologist from assigning it to its proper place in the crinoid's calcareous skeleton 

 The ray joints are long and slender as compared with the P. latifrons. They are 

 deeply sulcated on their inner surfaces ; each joint, as is common to most of the 

 crinoidea, giving sujiport to a single tentaculum, these therefore from the joints being 

 long, were not numerous. 



11. Species. Poteriocrinus impressus. (Phillips.) 

 PL 10, fff. 6. 



Definition. — Body conical; articulations for the rays not extending quite across the 

 plates; rays articulating by double parallel ridges, and a minute central perforation. 

 Column and rays unknown. 



Synonymes and References. 

 Poteriocrinus impressus. — Phill. Geol. Yorks. PL ^.fig. 1. 



Formation and Localities. 



Mountain Limestone. — Whitewell ; Bristol; A rran; Ireland. 



Our information respecting this crinoid, is exceedingly meagre, nothing being known 

 of its rays, or column, or structure of the mouth. 



This species of Poteriocrinus was first discovered by the late Mr. Gilbertson, and 

 described by Prof. Phillips, in his work on the Geology of Yorkshire. Mr. Gilbertson's 

 specimens are now deposited in the British Museum, having been purchased by the 

 Trustees of that Institution. 



12. Species. Poteriocrinus dactyloides. (Austin.) 

 PL 10. fig. 7. and PL U. fig. I a, lb. 



Definition. — Body attenuated ; rays five, deeply sulcated and articulating by the whole 

 breadth of the plates ; column thin jointed and but slightly enlarging in diameter at 

 and near its attachment to the body. 



