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IV. GENUS POTERIOCRINITES. 

 VASE-LIKE LILY-SHAPED ANIMAL. 



Generic Character. 



A Crinoidal animal, with a round column composed of numerous thin 

 joints, having in their centre a round alimentary canal, and articulating by sur- 

 faces striated in radii. Round auxiliary side arms proceeding at irregular dis- 

 tances from the column. Pelvis * formed of five pentagonal plate-like joints, 

 supporting five hexagonal intercostal plate-like joints, and five plate-like sca- 

 pulae, having on one of the intercostals an interscapulary plate interposed. An 

 arm proceeding from each of the scapulae. 



Base, probably fascicular, and permanently adhering. 



Observation. 



The generic name is derived from FIOTHPION, a drinking vessel, having been 

 suggested by the resemblance of its figure to that of a common conical wine 



glass. 



This genus, as far as I have been able to ascertain, contains two species 

 only, P. Crassus, and P. Teuuis ; the former, as was observed, serves as a type 

 for the generic character, the latter bears analogy to it in general formation, but 

 from its plates only adhering by sutures, and not showing articulations, renders 

 the transition to the division INARTICUJLATA perfect. No recent individual be- 

 longing to this genus has been as yet discovered. 



* It is with considerable hesitation that I describe these five plates as belonging to the Pelvis, 

 the analogy of their lower articulating surfaces, seems, perhaps, rather to indicate their belonging 

 to the first costal series. I have never yet bail an opportunity of seeing the connection of these 

 plates with the first columnar joint fairly developed, and it seems possible that the true pelvis 

 may be small and almost concealed. This doubt will be done away by the acquisition of more in- 

 structive specimens, and uiy thus stating the case must be considered as resulting from an anxious 

 desire to check errors. It is not unlikely that the real joinls forming the pelvis are so much abbrevi- 

 ated as not to be visible externally. Every one acquainted with fossils must be aware how difficult 

 it is to trace always organic details in them correctly, and bow many specimens are sometimes ne- 

 cessary to ascertain a single fact, 



