88 
EXPLANATION OF PLATE 53. 
base of the side arms, with the larger joints of the 
vertebral column. See V. I. p. 439. Note. (Original.) 
Fig. 8. Magnified Section of a portion of a Column in 
the Oxford Museum. The joints, as in PI. 52, Fig. 
4, 5, and in PI. 49, Figs. 3, 4, are alternately thicker 
and thinner; with a third, and still thinner joint 
interposed between them. See V. I. p. 435 , Note. 
(Original.) 
Fig. 8”. Nat. size of Fig. 8. 
Fig. 8 . Portion of a Column, shewing the manner in 
which the edges of the thinnest plates, c, are visible 
along the salient angles only. In the intermediate 
grooves the thicker plates, of the first and second 
sizes, a, h, overlap and conceal the edges of the 
thinnest plates, c. The principle of this mechanism 
is the same as in Pentacrinites subangularis, PI. 
52, Figs. 4, 5, and in Encrinites monilifonnis, PI. 
49, Figs. 3, 4 ; but the circular form of the column 
m the latter, causes the smallest plate, c, to be 
visible around its entire circumference. See V. I. 
p. 435, Note. (Original.) 
The bases of two side arms are seen in two of the 
grooves, articulating with the uppermost large joint 
of this column. On other large joints are seen the 
sockets from which similar side arms have fallen. 
Figs. 9, 10, 11, 12, 13. Various stellated forms on the 
aiticulating surfaces of Vertebrae, preserved in the 
dislocated mass beneath Figs. 1, 2. These petal- 
shaped, and crenated rays were probably adapted 
to produce various degrees of flexibility, according 
to their respective places in the column. The small 
Vertebra on Fig. 13, is derived from another indi- 
vidual. (Original.) 
The aperture at the centre of all these Vertebice 
was for the passage of the alimentary canal, which 
