VIII ECHINODERMATA— SYSTEMATIC REVIEW 311 



with root-like processes at its base, or with iiTegularly arranged cirri ; its proximal 



P 





CO 



Fig. 257. — Metacrinus Murray! (after P. H. Carpenter). Most of the arms and tlie larger pait 

 of the stem broken off. p, Pinnulse ; ci, cirri : ng, node. 



ossicle usually enlarged. Upper Jurassic, Chalk, Tertiary, Recent. Rhizocrinus, 

 BoiirgueticriniLS. 



