554 THE MEDUSA'S HEAD. 



Every one who has the least smattering of geology is familiar with the fossils called 

 Encrinites, and is well acquainted with them under the different popular names that they 

 bear. They are. or rather were, Echinodermata set upon a long flexible stalk, and being 

 constructed, like the Star-fishes, of an enormous number of joints. Popularly they are 

 known by the name of Stone-lilies, or Screw-stones, and their disjointed members are very 

 familiar under the title of St. Cuthbert's Beads. The number of joints in an adult Encrinite 

 is almost incredible. 



In the head only of one specimen, no less than one hundred and fifty thousand joints have 

 been calculated to exist, exclusive of the numerous paints of which the stem is composed. 

 These joints are frequently found separated from each other ; and as they are perforated by a 

 small hole through which a thread might be run, they were formerly strung together and 

 used as rosaries. Encrinites were found very plentifully in many marbles, which, according to 

 Dr. Buckland' s energetic language, are as entirely made up of the petrified remains of Encrin- 

 ites as a corn-rick is of straws. These wonderful beings could hardly be dissected out of the 

 stone by any exertion of human labor, but it is found that water will achieve a task at 

 once too laborious and too delicate for human hands to undertake. It oftens happens that 

 the abrupt faces of marble cliffs exposed to the weather, so that the annual rains are 

 driven forciby upon them, and by their continual action wear away the soft surrounding 

 substance of the stone, leaving the harder forms of the Encrinites as memorials of the time 

 long passed away. 



The Encrinites have long ago perished, but there are still some existing species of stalked 

 Echinodermata, which are closely allied to them, and are still more nearly connected with 

 the history of the Feather-star. These are termed Pentacrinites, because their joints are 

 five-sided. Many fossil species of Pentacrinites are found, and are seen in positions which 

 seem to prove that they must have been adherent by their bases to floating objects, and thus 

 carried about from one place to another, like the barnacles, which have already described and 

 figured. 



The Feather-star is a great rarity. The Comatula is a stemmed form found sparingly 

 in the waters off South Carolina. A large species is found off Greenland, and is occasionally 

 brought from off the coast of Maine, near Eastport. 



ONE living species of these strange creatures is still in existence. This being is appro- 

 priately called by the name of MEDUSA'S HEAD, as the many arms that wave about its 

 summit bear some resemblance to the fabled head of Medusa, with its burden of venomous 

 serpents. 



It is not a very large species when compared with some of its fossil relatives, for the largest 

 specimens hitherto discovered are only a few feet in length, and have a stem about as large as 

 a common drawing-pencil. Several fossil species, on the contrary, are at least eleven or twelve 

 feet in length, and measure a full inch across the stem. The Medusa's Head is the only species 

 at present known, though it is probable that others may be yet discovered. 



Euriale scwtatum is a name applied to a very singular and always interesting form of 

 Star-fish. A species found off Massachusetts Bay is named AstropJiyton agassizi. Basket-fish, 

 so called by old Governor Winthrop, of Massachusetts, who wrote an account of it with other 

 natural productions, for the Proceedings of the Royal Society. Linna3us called it Asterias 

 caput medusce, a very good specific name Medusa's Head. This has been regarded as very 

 rare. An occasional instance of its being drawn up by fishermen, was all that was known 

 until it was taken in quantities off Cape Cod in one locality. 



A Star-fish, discovered by Mr. Thompson, and called by him Pentacrinus europceus, is, 

 when full-grown, barely three-quarters of an inch in height, and with a stem no thicker than 

 sewing silk. AVithout entering into the many and interesting details of structure, development, 

 and the habits of this beautiful little creature, we need only observe that this being has been 

 proved to be the young, or larval state of the Feather-star. During this stage of its existence, 

 the young Comatula is affixed to its ever-lengthening stem, but when it has attained adult age, 

 it leaves its footstalk and wanders freely through the ocean. 



