26 S 



Pentacrinus caput Medusa. The comparison of the living individual 

 with the fossil fragments 

 described by his predeces- 

 sors, and of which he had 

 specimens in his collections, 

 enabled him to ascertain the 

 real origin of the fossil En- 

 crinoideae. The beautiful 

 fragment of this recent form 

 which still exists in the Mu- 

 seum of Natural History at 

 Paris was long considered 

 unique, but it is now known 

 that many others exist in 

 the different museums of 

 Europe and America. Since 

 that date the Crinoi'deze 

 have beenexaminedand de- 

 scribed by observers such as 

 Miller, Forbes, d'Orbigny, 

 Agassiz, Sars, Pictet, Major 

 Austin, and by Carpenter 

 and Wyville Thomson. 



Among the species of 

 fixed Crinoi'deae actually 

 living are Pentacrinus 

 caput: Medusa (Fig. 106) 

 and Rhizocrinus lofotensis. 

 These curious Echino- 

 derms resemble a flower 

 borne upon a stem, which 

 terminates in an organ 

 called the calyx, which is, 

 properly speaking, the body 

 of the animal. Arms, more 

 or less branching, spring 

 from this calyx, their ramifi- 

 cations, so formed, con- 

 sisting of many pieces aiti- Fig. 106. Pentacrinus caput Medusae (Miiller). 



culated to each other. The 



calyx is supported by a stem, varying in height, formed of pieces 



secreted by the living tissues which surround them. The articulations 



