434 
BRIAREAN PENTACRINITE. 
of fossil skeletons, infer the nature and functions 
of the muscles by which motion was imparted to 
each bone. 
I shall select from the many fossil species of 
the Genus Pentacrinite, that, which from the 
extraordinary number of auxiliary side arms, 
placed along its column, has been called the 
Briarean Pentacrmite, and of which our figures 
(PI. 51. Figs. 1, 2. ; PI. 52. Fig. 3. ; and PI. 53.) 
will give a more accurate idea than can be con- 
veyed by verbal descriptions.* 
* PI. 51 represents a single specimen of Briarean Pentacrinite, 
which stands in liigh relief upon the surface of a slab of Lias, 
from Lyme Regis, almost entirely made up of a mass of other 
individuals of the same species. The arms and fingers are con- 
siderably expanded towards the position they would assume in 
searching for food. The side arms remain attached to the upper 
portion only of the vertebral column. 
At PI. 53. Fig. 1 and 2 represent two other specimens of the 
same species, rising in beautiful relief from a slab, which is com- 
posed of a congeries of fragments of similar individuals. The 
columns of these specimens, Fig, 2, a, shew the side arms rising 
in their natural position from the grooves between the angular 
projections of the Pentagonal stem. At PI. 52. Fig. 1. F. F- 
are seen the costal plates sun-ounding the cavity of the body '> 
at H, the Scapulte, with the arms and fingers proceeding from 
them to the extremities of the tentacula. 
At PI. 53. Fig. 3. exhibits the side arms rising from the lower 
part of a vertebral column, and entirely covering it. Fig. 4. m 
another column, on which, the side arms being removed, we see 
the grooves wherein they articulated with the alternate vertebrm- 
Fig. 5. exhibits a portion of another column slightly contorted. 
