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72 
tion and articulation resembles the corresponding joint of the Pentacrinites. 
Its length, not unfrequently, exceeds its thickness six times, whence it bears a 
distant resemblance to a split os humeri of a very small size. 
Fincer Joint.—From its summit proceed the first joints of two fingers, 
(fig. 24. and 2b.) they are equally slender, adhering near the base laterally to 
each other. On these the following finger joints (fig. 22. and 23.) are inserted 
in single series, they are much excavated at the inner surface, and by the 
alternately inclining angle of their superior surface, indicate that the tentacula 
came off alternately from the broader portion of every joint. The specimen 
in my possession does not display the tentacula, nor have I been able to trace 
their place of insertion on the finger joints, but I apprehend that these being 
so thin, and not offering a safe point of attachment, a muscular adhesion 
existed in this species. Ihave also found minute plates indicating that the 
cup-like abdominal cavity, and the excavated sulci in the arm and fingers 
have been protected by a plated integument, similar to that noticed in other 
Crinoidea. 
