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IV. GENUS POTERIOCRINITES. 
VASE-LIKE LILY-SSHAPED 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 joiuts, and five plate-like sca- 
pul, having on one of the intercostals an interscapulary plate interposed. An 
arm proceeding from each of the scapule. 
Base, probably fascicular, and permanently adhering. 
Observation. 
The generic name is derived from norupion, 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. Tenuis; 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 LNarticuxa'ra 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 had 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 my thus stating the case must be considered as resulting from an anxious 
desire to check errors. It is not unlikely that the real joints forming the pelvis are so much abbrevi- 
ated as not to be visible externally. very one acquainted with fossils must be aware how difficult 
itis to trace always organic details in them correctly, and how many specimens are sometimes ne- 
cessary to ascertain a single fact. 
