GEOLOGICAL DISTRIBUTION OF ECHINODERMATA. 477 



Encrinites, as a corn-rick is composed of straws. Man applies 

 it to construct his palace, and adorn his sepulchre ; but there are 

 few who know, and fewer still who duly appreciate, the sur- 

 prising fact, that much of this marble is composed of the skele- 

 tons of millions of organised beings, once endowed with life and 

 susceptible of enjoyment, which, after performing the part that 

 was for a while assigned to them in living nature, have con- 

 tributed their remains towards the composition of the mountain 

 masses of the earth." Fragments of Encrinites are also dis- 

 persed irregularly throughout all the deposits of the Transition 

 period, intermixed with the remains of other contemporary 

 marine animals. No other species of Echinodermata, however, 

 as yet present themselves; and it is interesting to remark, that 

 the Crino'idea which so abound in the Transition epoch, be- 

 longed, with one exception, to the Encrinus and other round- 

 stemmed genera, and were therefore more unlike the existing 

 forms of that family, than were those which we find at a later 

 period. All these Crino'idea, which continue to abound in the 

 Mountain Limestone and other of the more ancient secondary 

 rocks, become extinct when we arrive at the Lias ; and are then 

 replaced by the Pentacrinus. The stems of Encrinites compose 

 extensive beds in the Carboniferous, as in the Transition series ; 

 and these are often found in the neighbourhood of those of a dis- 

 tinctly Coralline nature, so that the animals probably grew on 

 the banks of such reefs as are now being elevated in the South- 

 ern Ocean, and which, if properly examined, might be found to 

 support their living analogues. The joints of the Encrinite- 

 stems often fall asunder when the connecting rock is not firm 

 enough to hold them, the animal membrane which united them 

 in the living state having long since decayed away. Their flat 

 round form, and central perforation, have occasioned them to re- 

 ceive the name of Entrochi, or wheel-stones. They were form- 

 erly strung as beads for rosaries ; and in the northern parts of 

 Britain they still retain the appellation of St. Cuthbert's beads. 



" On a rock by Lindisfarn 

 Saint Cuthbert sits, and toils to frame 

 The sea-born beads that bear his name." 

 VOL. II. L L 



