241 
LETTER XXIII. 
PENTACRINITES.... DIFFERENT VERTEBRAE NOTICED. 
Agreeable to the distinction which it has been already determined 
to adopt, I have first examined all the species of this kind of fossil, 
which, from their trochital vertebrae, required to be placed among the 
encrinites ; I shall now proceed to examine such as, from their penta- 
gonal vertebrae, may be considered as pentacrinites. These, as far as 
our limited knowledge of them will allow me to judge, may be de- 
scribed as the mineralized osseous parts of a zoophyte, which possessed 
a pentagonal, articulated, certehral column, from the superior part of 
which, from five bases, proceeded as many articidated arms speedily rami- 
fying into innumerable smaller branches, closely beset with articulated ten- 
tacula, bearing, in the mass, much of a plumose appearance. 
Adopting, as nearly as I am able, the same order in the investiga- 
tion of these bodies, as was employed whilst examining the several spe- 
cies of encrinites, I shall, in the first place, make inquiry respecting 
the nature and history of the fossil vertebrae of these animals. Small 
flat stones have long been found, being angular and. almost con- 
stantly pentagonal; bearing on their flat surfaces a stellated figure, 
somew'hat resembling the five expanded petals of a flower. To these 
stones was given the name of AsTERiiE, or Star-stones ; and when 
VOL. II. I I 
