Numerous species of star-fishes are so very common in our waters, that in many places the sea-bottom is literally paved with them. They likewise abounded in the primeval ocean, for deep beds of carboniferous limestone and vast strata of the triassic muschelkalk are often formed by the accumulation of little else than the skeletons of Encrinites and Pentacrinites, which, unlike the sea-stars which every storm drifts upon our shores, did not move about freely, but were affixed to a slender flexible stalk, composed of numerous calcareous joints connected together by a fleshy coat. The feathered bifurcated arms of the Crinoids are unprovided with suckers, which would have been perfectly useless to creatures not destined to pursue their game to any distance, but passively to receive the nutriment which the current of sea-water set in motion by their richly-ciliated pinnules conveys to the mouth. These beautiful creatures were formerly supposed to be nearly extinct, for up to within the last few years only two living stalked crinoids were known in the ocean of the present period, but the dredge has latterly brought up new and remarkably fine species from depths of more than 2000 fathoms, and there is every reason to believe that these animals still form an important element in the abyssal fauna.[S] [Footnote S: See page 420.] [Illustration: Portion of the Pentaorinus Briareus. (Fossil.)] Of freely-swimming Crinoids but one single representative is known in the northern seas, the Rosy Feather-star (_Comatula rosacea_), whose long and delicately fringed rays and deep rose colour dotted with brown may serve to give us an idea of the beauty of the submarine landscapes where _Pentacrinus Wyville-Thomsoni_ or _Bathycrinus gracilis_ abound. During the earlier stage of its existence, the comatula is attached to a stalk; a discovery for which science is indebted to Mr. T. V. Thompson, who in 1823 dredged in the Cove of Cork a singular little pedunculated crinoid animal (_Pentacrinus europæus_), which he found attached to the stems of zoophytes. It measured about three-fourths of an inch in height, and resembled a minute _comatula_ mounted on the stalk of a _pentacrinus_. When this pygmy representative of the ancient lily-stars was first dragged up from its submarine haunts, it created a great sensation among naturalists, as it was the first recent animal of the encrinite kind which had ever been seen in the seas of Europe. At first it was supposed to be a distinct species, but Mr. Thompson, by carefully following it through all the stages of its growth, succeeded in proving that it was merely the hitherto unnoticed young of the rosy feather-star.