degree of perfection than is retained in the existing Pentacrinites; and although the place, which, as Zoophytes, they occupied in the animal kingdom, was low, yet they were constructed with a perfect adaptation to that low estate, and in this primeval perfection they afford another example at variance with the doctrine of the progression of animal life from simple rudiments through a series of gradually improving and more perfect forms, to its fullest development in existing species. Thus, a comparison of one of the early forms of the Genus Pentacrinite; viz. the Briarean Pentacrinite of the Lias, (Pl. 51 and Pl. 52, Fig. 3. and Pl. 53) with the fossil species of more recent formations, and with the existing Pentacrinus Caput Medusæ from the Caribbean Sea, Pl. 52, Fig. 1, shows in the organization of this very ancient species an equal degree of perfection, and a more elaborate combination of analogous organs, than occurs in any other fossil species of more recent date, or in its living representative.
Pentacrinites.
The history of these fossil bodies, that abound in the lower strata of the Oolite formation, and especially in the Lias, has been much illustrated by the discovery of two living forms of the same Genus, viz. the Pentacrinus Caput Medusæ,[1] (Pl. 52, Fig. 1,) and Pentacrinus Europaeus, Pl. 52, Figs. 2. 2'. Of the first of these a few specimens only have been brought up from the bottom of deep seas in the West Indies; having their lower extremities broken, as if torn from a firm attachment to the bottom. The Pentacrinus Europaeus.[2] (see Pl. 52, Figs. 2. 2',) is found attached to various
