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LETTER XXIV. 
BIlIARiEAN PENTACRINITE VERTEBRAL COLUMN VERTEBRAL 
PROCESSES TWOEOLD OFFICE BONES FORMING THE PELVIS..,. 
SUPERIOR EXTREMITIES ANASTOMOSING PENTACRINITE. 
The species of pentacrinite which first demands our attention is the 
one which most abounds in this country. This circumstance, and 
that of its being the species which has been longest known to orycto- 
logists, give it a fair claim to this preference. The distinguishing cha- 
racteristic of this species appears to be its 'vertebral processes passing 
out from every part of its column. 
In the trunk of this animal are several circumstances of a 
very interesting nature. The constant intermixture, in various ways, 
but chiefly in an alternate order of thicker and thinner vertebrae, is 
observable, I believe, in most of the specimens of this fossil : but so 
nicely are these vertebrae arranged and fitted, that, except where they 
have been displaced by accident, they always seem, to preserve an 
exact linear regularity. It is not, indeed, common to see any well 
connected column of this species detached from its matrix, but 
in no one specimen, however long it may have been, have I ever seen 
the least diminution or tapering of the column. This last-mentioned 
circumstance is particularly deserving of attention, since from it may 
