EXPLANATION OF PLATE 53, 
87 
and entirely composed of a mass of petrified Ossi- 
cula of the same species of Pentacrinite. The sur- 
face of these fossils is covered with a delicate film 
of Iron Pyrites, which gives them the appearance of 
beautiful Bronze. (Original.) 
1“. Continuation of the stem of Fig. 1. 
2“. Portion of the stem of Fig. 2. 
The length of these stems when entire, was three 
or four times that of the fragments here remaining. 
Upon the stem 2", nearly all the side arms retain 
their places in the grooves on each side of the salient 
angles of the pentagonal column ; they diminish in 
size as they approach its upper extremity. This is 
also distinctly seen at the upper end of the column 
of Fig. 1. 
~ First costal plate. Second costal plate. 
Fig. 3. Portion of a third column retaining nearly all its 
auxiliary side arms in their natural place. 
Fig. 3“, Continuation of the same column deprived of 
the side arms. 
Fig. 4. Portion of another column, with traces of a few 
side arms rising from the lateral grooves. 
Fig. 4“. Continuation of Fig. 4. 
Fig. 5. Fragment of another column, the joints of which 
are so much bent without dislocation, as almost to 
give the column the appearance of a spiral disposi- 
tion. 
Fig. 6. Body of a Briarean Pentacrinite and summit of 
its column, shewing the interior of the ossicula that 
surround the abdominal cavity. 
E. Pelvis, i First costal Plate. From a specimen in the 
Oxford Museum. (Original.) 
Eig. 7. Fragment of a column hi the collection of Mr. 
J. Sowerby, shewing the oblique articulation of the 
