Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/331

 Figs. 1, 2.; Pl. 52. Fig. 3.; and Pl. 53.) will give a more accurate idea than can be conveyed by verbal descriptions.

Vertebral Column.

The upper part of the vertebral column of Pentacrinites is constructed on principles analogous to those already described in the upper part of the column of the Encrinite.

All the joints of the column, when seen transversely, present various modifications of pentagonal star-like forms; hence their name of Asteriæ, or star-stones.

These transverse surfaces are variously covered with a