The author remarks, that although there are upwards of 280 writers on the Crinoidea, yet there is no class of ancient animals so much misunderstood. These animals have not merely played an important part in the system of creation as regards animal life, but they have also modified the physical condition of the globe. They are found abundantly in limestones, both of the Silurian and of the Carboniferous epochs, attaining their maximum in the latter.