74 



RAMBLES AND REVERIES. 



only touching upon these points where it may be 

 necessary to indicate any variations from the normal 

 characters of living Oinoids that older forms may 

 exhibit. 



The earliest Encrinite is the Dendrocrinus of the 

 Cambrian age. 



In the Silurian deposits, particularly in the 

 Wenlock limestone, vast numbers of encrinites 

 have been obtained, and many of them of extreme 

 beauty. The chief genera represented are Glypto- 

 crinuS) Crotalocrinus, Marsupiocrinus, Cyathocrinus, 

 Platycrinus, Taxocrinus, Ictkyocrinus, and Edrio- 

 crinus. We have selected as illustrations Marsupio- 

 crinus (marsupium, pouch) and Crotalocrinus, so 

 called from its similarity in shape to a child's rattle 

 (Greek krotalon, rattle). The arms of C. rugosus 

 begin at the top of the body, and the ossicles are 

 fastened to each other both at the sides and verti- 

 cally, thus giving the appearance of a basket-work 

 rattle (Fig. 14). 



The Devonian rocks also furnish large quantities 

 of encrinites. 



In the Carboniferous deposits encrinites are so 

 numerous that it has even been suggested that the 

 period to which they belong should be called " the 

 age of Crinoids." From the Yoredales of Hebden 

 Bridge very fine specimens have been obtained. 

 It would seem as if the muddier sediments of the 

 Yoredale deposits had proved suddenly fatal to vast 

 quantities of these delicate organisms, just as we 

 know would now be the case were the water in 

 which the coral polypes are carrying on their mar- 



